The surrogate spellcasting feat (Savage Species) lets him complete verbal components with meows and somatic components by waving his paws. The eschew materials feat lets him ignore material components costing up to 1 gp.
He could replace the 5th level of wizard with a level of unseen seer (Complete Mage) if he can swing the skill requirements. If he takes 2 levels of unseen seer, he can pick up the spell hunter's eye (Player's Handbook II) for an extra 1d6 per 3 caster levels sneak attack damage.
He may enjoy the acidic splatter feat (Complete Mage). It's not a ray, but a ranged touch attack dealing 1d6 acid damage per level of the highest-level acid spell he can cast still seems to be up his ally.
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