The Beguiler doesn't get sneak attack....it's pretty much a skill monkey illusionist/enchanter.
A skill monkey with invocations sounds like a lot of fun!!!
Maybe go with the spellthief progression of sneak attack?
Before the official magus came out, I came out with a Jedi-like version. It basically got a 1/2 powered eldritch blast, but could 2-weapon fight with it, get iterative attacks, etc.
You could probably replace the spells with invocations and maybe boost the skill points from 4 to 6 per level and expand the spell list to get what you want.
Magician
BAB: +3/4
Good Saves: Will
Hit Dice: 1d8
Class Skills: Acrobatics, Appraise, Climb, Craft, Escape Artist, Knowledge all, Linguistics, Profession, Ride, Spellcraft, Swim.
Skill Ranks per Level: 4 + Intelligence modifier.
A Magician is proficient in all Simple Weapons and his Magic Staff. A Magician is not proficient in any armor or shields.
A Magician casts arcane spells using the Bard’s Spells Per Day and Bard’s Spells Known tables. A Magician must have a Intelligence score of 10 + the spell level to know or cast a spell. The Save DC of a Magician’s spell is 10 + the spell level + the Magician’s Intelligence modifier. A Magician gets bonus spells based on Intelligence. The Magician learns spells from the list of Magician spells. The list of Magician spells deals primarily with buffing, de-buffing, mobility enhancing, protective, target acquisition, and single target or extremely close range damaging spells, primarily touch and ranged touch spells, or spells with a range of Close or shorter.
LEVEL ABILITY
1. Arcane Might, Aura, Cantrips, Magic Staff 1d6, Canny Defense
2. Aura
3. Staff Power
4. +1 AC, Aura
5. Magic Staff 2d6
6. Aura
7. Staff Power
8. +2 AC, Aura, Improved Auras
9. Magic Staff 3d6
10. Aura
11. Staff Power
12. +3 AC, Aura
13. Magic Staff 4d6
14. Aura, Greater Auras
15. Staff Power
16. +4 AC, Aura
17. Magic Staff 5d6
18. Aura
19. Staff Power
20. +5 AC, Aura, Ultimate Aura
Arcane Might (Ex). The Magician uses his Caster Level to determine his Combat Maneuver Bonus, Combat Maneuver Defense, and his BAB for the purposes of qualifying for feats.
Aura (Su). At 1st level, the Magician learns 1 aura. At 2nd level, and every two levels thereafter, the Magician gains an additional aura. At 8th level, he can begin selecting Improved Auras. At 14th level, he can begin selecting Greater Auras. At 20th level, he gains an Ultimate Aura in addition to selecting an Aura, Improved Aura, or Greater Aura. An Aura is a magical effect that targets all creatures adjacent to or touching the Magician. A Magician can activate an aura as a swift action and deactivate it as a free action. Unless otherwise stated, a Magician can only have a single Aura activated at one time. The Save DC of an Aura is 10 + ½ the Magician’s level + his Intelligence modifier.
Canny Defense (Ex). The Magician adds his Intelligence bonus, if any, to his AC if he is unarmored and carrying a light load or less. This bonus applies to his touch AC and even when the Magician is flatfooted; it does not apply if the Magician is helpless or immobilized. This bonus to his AC increases by +1 at 4th level and every 4 levels thereafter.
Cantrips (Sp). The Magician learns a number of 0-level arcane spells that he can cast at will. These are selected from the list of Magician spells.
Magic Staff (Sp). As a swift action, the Magician can summon a magical staff that deals bludgeoning damage and lasts a number of rounds equal to the Magician‘s Intelligence bonus (minimum 1 round). The Magic Staff makes touch attacks and has a threat and critical range of 20/x2. The Magician can use the Weapon Finesse feat with his Magic Staff. It initially does 1d6 points of damage; this increases by 1d6 at 5th level and every 4 levels thereafter. The Magic Staff is immaterial and weightless and the Magician does not add his Strength bonus to damage. The Magician can deliver touch spells through his Magic Staff. The Magic Staff is weightless and has a hardness and hit points equal to the Magician’s class level + his Intelligence bonus.
Staff Power (Sp). At 3rd level, and every 4 levels beyond 3rd, the Magician can choose one of the following abilities and apply it to his Magic Staff.
Cunning Cudgel. The Magician adds his Intelligence bonus to his attack and damage rolls with his Magic Staff. He also adds his Intelligence bonus to his CMB and CMD when using his Magic Staff.
Double Staff. The Magician’s Magic Staff can be used as a double weapon. The Magician gains the use of the Two Weapon Fighting feat when using his Magic Staff. At 6th level, he gains the use of the Improved Two Weapon Fighting feat when using his Magic Staff. At 11th level, he gains the use of the Greater Two Weapon Fighting feat when using his Magic Staff.
Flashing Staff. The Magician can throw his Magic Staff as if it were a javelin, making a ranged touch attack with a range increment of 30 feet and 5 range increments maximum. Once it leaves his hand, the Magic Staff disappears after 1 round. The Magician gains the use of the Precise Shot feat when using his Magic Staff. At 6th level, he gains the use of the Shot on the Run feat when using his Magic Staff. At 11th level, he gains the use of the Improved Precise Shot feat when using his Magic Staff.
Heart Staff. The Magician’s Magic Staff bypasses DR as if it had the Magician’s alignment and causes an additional 1d6 points of damage to an opponent that has an alignment in direct opposition to the Magician’s. If both alignment axes (chaos/law and evil/good) are in opposition to the Magician’s, the opponent takes 2d6 points of additional damage.
Peace Staff. The Magician’s Magic Staff causes non-lethal damage.
Piercing Staff. The Magician’s Magic Staff causes piercing damage and has a critical multiplier of x3.
Quick Staff. The Magician can summon his Magic Staff as a free action on his turn or an immediate action if it is not his turn. He adds his Intelligence bonus to his initiative rolls.
Reach Staff. The Magician’s Magic Staff’s reach increases by 5 feet. The Magician gains the use of the Combat Reflexes feat when using his Magic Staff. At 6th level, he gains the use of the Stand Still feat when using his Magic Staff. At 11th level, he gains the use of the Strike Back feat when using his Magic Staff.
Shaft of Moonlight. The Magician’s Magic Staff bypasses DR as if it were made of Silver.
Slashing Staff. The Magician’s Magic Staff causes slashing damage and has a threat range of 19-20.
Staff of the Earth’s Shadow. The Magician’s Magic Staff bypasses DR as if it were made of Cold Iron.
Starlight Staff. The Magician’s Magic Staff bypasses DR as if it were made of adamantine. The Magician must be at least 11th level before selecting this power.
Sunray Staff. The Magician can deliver ranged touch spells through his Magic Staff with a melee touch attack.
Auras.
Aura of Sadness. Creatures adjacent to the Magician suffer -2 to Attack Rolls, Saving Throws, and Skill Checks.
Aura of Shadows. 20% miss chance to target the Magician and the Magician gains a bonus equal to his level on Stealth checks.
Aura of Shifting Stones. Adjacent squares are considered difficult terrain and the Magician benefits from flawless stride.
Improved Auras.
Aura of the Sun. Adjacent creatures take 2d6 points of fire damage each round. The Magician’s weapons deal +1d6 points of fire damage, and he gains fire resistance 20.
Aura of Ice and Snow. Adjacent creatures take 1d6 points of cold damage and must make a Reflex Save or fall prone. The Magician’s weapons deal +1d6 points of cold damage, and he gains cold resistance 20.
Aura of Creeping Growths. Adjacent creatures are entangled and the Magician gains woodland stride.
Greater Auras.
Aura of Corruption. Adjacent creatures take 2d6 points of acid damage each round and must make a Fortitude save or become nauseated for 1 round (sickened on a successful save). The Magician’s weapons deal +1d6 points of acid damage and the Magician gains acid resistance 30.
Aura of Repulsion. Adjacent creatures are subjected to a bull rush with a CMB equal to the Magician’s level + his Intelligence modifier. The Magician gains a deflection bonus to his AC equal to his Charisma bonus (minimum +1).
Aura of True Night. The Magician is totally obscured by magical darkness, granting him total concealment. The Magician gains the ability to see through magical and non-magical darkness.
Ultimate Auras.
Aura of the Shattered Diamond. Any weapon striking the Magician takes damage equal to his class level + his Intelligence bonus that bypasses any hardness of 20 or less. If this destroys the weapon, the Magician takes no damage. Creatures adjacent to the Magician take 5d6 points of damage from spinning blades of force (Reflex for half).
Aura of Scattered Foes. All adjacent creatures are teleported 20 feet away and must make a Reflex save or become prone. The Magician benefits from the Improved Blink spell.
Aura of the Vampire. All adjacent creatures gain a negative level each round. The Magician gains 5 hit points for each negative level bestowed. Temporary hit points above his maximum disappear after 1 hour.
I played a ranger 1/warlock x from level 4-ish to 12-ish, and another warlock from 20th-25th or so, and they both did OK. The warlock actually has lots and lots of staying power. I put my highest score in Constitution, and was pretty much a tank/mobile artillery. The eldritch blast is actually pretty good because it's at will, so you can use it for lots of interesting uses, like pounding through doors, using the acid invocation with the cone invocation to re-design the floor with pits, stuff like that. The MIC has some nice boosts to the EB that aren't over powering (like a few extra dice of damage for a fair price).