A wish could probably do it, although the GM may have many ways to twist the outcome (or even just have the character become a wyrmling dragon with class levels, as dragon age categories are independent of experience points). There are several ways to gain wishes before gaining 9th-level spells, but some are more at risk of being twisted than others.
One thing to keep in mind: the Eschew Materials feat may also be a "must have." Characters starting as humanoids are not trained to "cast" the same way as dragons using their innate spells. A polymorphic pouch (or an equivalent) may also be useful for material components that have a gp value.
Alternately, or in addition, a dip in bard or skald can open up the dragon disciple prestige class. Note that although being able "to cast 1st-level arcane spells without preparation" is a prerequisite, you are not required to advance the spellcasting of that arcane class; you can improve your wizard spellcasting. Personally, I'd prefer skald (probably spell warrior for enhance weapons) to also qualify for eldritch knight* (a dragon wizard 4/skald 1/dragon disciple 4/eldritch knight X... hmmm).
*- You're a freaking dragon! You should be at least somewhat capable as a combatant, IMO, even at the cost not being the "best" spellcaster.
There are ways to make your spells harder to dispel. You can start with various caster level boosts, maybe pick up the tenacious spell metamagic feat, if allowed maybe get something out of the D&D 3.5 magic item compendium or spell compendium. It's still possible but it gets less likely.
1) Speak with G.M. - if they are not on board then this is not happening.
3) Be cursed by a [7/8] Bestow Curse (Greater) to have your Wizard's selfishness condemn him.
4) Become increasingly obsessed with adding to your own "horde".
5) Acquire the Half-Dragon Template as a consequence of consistently falling prey to and aligning with cursed draconic energies.
6) Quickly be killed - for your valuable scales/in fear by those who lost people to Dragon attacks/by a disgusted True Dragon/by an egotistical Linnorm looking to prove itself against "Dragons".
7) Spend some time playing another Character - your own Cohort, a hired adventurer, a relative of your Character, a loyal Simulacrum of the Wizard, a Ring of the Shadow Victim duplicate; etc. Preferably link to "saving" your Wizard Character, (e.g., "the curse might have condemned him to a torturous afterlife"), by bringing the rest of the Party on board whilst still contributing to their survival/fun.
8) Have the Party arrange for [4/5] Reincarnate to be used on your Wizard - at a time where his new C.R., (determined by your G.M.), aligns with the other Characters' progression/level ups. You will be a Young Adult Dragon.
9) Remember that your Character will retain its own Mental Ability Scores/memories/Class H.D./etc. Your will also be too large to continue adventuring in this form, so apart from consistently Preparing Polymorph Spells, you may want to ask your G.M. to select a Dragon with Change Shape (Su), (such as an Imperial Forest Dragon); for this perk you might be expected to have a traditionally Evil Dragon form to counterbalance it.
Note that although being able "to cast 1st-level arcane spells without preparation" is a prerequisite, you are not required to advance the spellcasting of that arcane class; you can improve your wizard spellcasting.
Just a thought, but would PREFERRED SPELL let you qualify for Dragon Disciple?
Also if you are going DD as a wizard i'd probably go DD-8 rather than DD-4/EK-10. That +2 CON is gonna help you survive, and the +2 INT is really really nice. You could go EK after that rather than the last 2 levels of DD.
if you're willing to put up with a one level dip in druid and having an alignment of NG you could do the following.
Alignment: NG
Classes: Draconic Druid(1), Dawnflower Anchorite(7)
Key Feats: Favored Prestige Class, Prestigious Caster, Shaping Focus
Credences: Focused Class Feature (Wildshape-Druid)
The focused class feature credence lets the prestige class count towards wildshape. Once you hit 3rd level then you actually gain the class feature allowing you to take shaping focus to push it 4 levels higher. This makes you effectively 7th level for purposes of the draconic druid's wildshape ability. Once you hit the 10th and 12th level marks draconic druid lets you fully wildshape into a dragon as per dragonform I and Dragonform II.
Unlike Dragon Disciple the Dawnflower Anchorite only costs you 1 caster level and since wildshape is hours per level you can effectively be a dragon all day. Also, since it's a supernatural ability you don't have to worry about someone coming along and dispelling you (though an anti-magic zone will still mess with you).
If it were me, I'd go with a wizards strengths and look more toward a crafting solution. Custom magic item could, with enough research and money get you pretty close. If you want it to be part of you, craft tattoo is an interesting option.
If I was the GM, I'd probably also be willing to discuss custom arcane discoveries. I'd have to think about balance issues of course, but extended duration on draconic form spells seems quite feasible. Maybe even some aspects of the half-dragon template as well, although the whole thing would be too much. Of course I'd be pretty open to purely cosmetic changes via a discovery, feat or even just a good explanation/magic.
Note that although being able "to cast 1st-level arcane spells without preparation" is a prerequisite, you are not required to advance the spellcasting of that arcane class; you can improve your wizard spellcasting.Just a thought, but would PREFERRED SPELL let you qualify for Dragon Disciple?
Also if you are going DD as a wizard i'd probably go DD-8 rather than DD-4/EK-10. That +2 CON is gonna help you survive, and the +2 INT is really really nice. You could go EK after that rather than the last 2 levels of DD.
The dragon disciple casting prerequisite is very specific: "cast 1st-level arcane spells without preparation." Not "cast spontaneously."
Wizard 4/skald 1/dragon disciple 4/eldritch knight 10 is down three levels of casting progression and still can gain 9th-level spells with one more level of wizard. Wizard 4/skald 1/dragon disciple 8/eldritch knight 7 is down four levels of casting progression and is limited to 8th-level spells. I'll take 9th-level spells over +2 Con and +2 Int.
Just a thought, but would PREFERRED SPELL let you qualify for Dragon Disciple?The dragon disciple casting prerequisite is very specific: "cast 1st-level arcane spells without preparation." Not "cast spontaneously."
Yeah I didn't really think it'd work, just throwing ideas out there.
Wizard 4/skald 1/dragon disciple 4/eldritch knight 10 is down three levels of casting progression and still can gain 9th-level spells with one more level of wizard. Wizard 4/skald 1/dragon disciple 8/eldritch knight 7 is down four levels of casting progression and is limited to 8th-level spells. I'll take 9th-level spells over +2 Con and +2 Int.
I was proposing the DD-8/Wizard-11 rather than DD-4/Wizard-5/EK10. They both lose 3 levels of wizard casting. The spontaneous-caster dip could cover light armour (if you want it) and some weapon proficiencies. The EK would have a higher BAB (15 vs 11 I think) but DD gets +2 INT, 2 extra bloodline feats, +1 Natural armour, Blindsense and Dragon Form 1/day.
I'm not saying EK is bad either, just putting ideas out there.