Spell information
SPECTRAL HAND
School necromancy; Level sorcerer/wizard 2
Casting Time 1 standard action
Components V, S
Range medium (100 ft. + 10 ft./level)
Effect one spectral hand
Duration 1 min./level (D)
Saving Throw none; Spell Resistance no
A ghostly hand shaped from your life force materializes and moves as you desire, allowing you to deliver low-level, touch range spells at a distance. On casting the spell, you lose 1d4 hit points that return when the spell ends (even if it is dispelled), but not if the hand is destroyed. (The hit points can be healed as normal.) For as long as the spell lasts, any touch range spell of 4th level or lower that you cast can be delivered by the spectral hand. The spell gives you a +2 bonus on your melee touch attack roll, and attacking with the hand counts normally as an attack. The hand always strikes from your direction. The hand cannot flank targets like a creature can. After it delivers a spell, or if it goes beyond the spell range or goes out of your sight, the hand returns to you and hovers.The hand is incorporeal and thus cannot be harmed by normal weapons. It has improved evasion (half damage on a failed Reflex save and no damage on a successful save), your save bonuses, and an AC of 22 (+8 size, +4 natural armor). Your Intelligence modifier applies to the hand's AC as if it were the hand's Dexterity modifier. The hand has 1 to 4 hit points, the same number that you lost in creating it.
Quick answer: the wizard can apply his sneak attack damage to spells cast through the spectral hand so long as he, the wizard, makes successful stealth checks.
Rather than seeing it as a separate individual, see it more as an arrow being loosed from a bow.
If the target is denied dex vs the wizard then it should work.
It is not a ranged touch attack so the 30 foot distance is not a problem by the rules, but a GM might decide that it should be that way.