Originally Posted by sonofzeal
Ah my apologies, I missed your post. My comments about dip-entry to Loremaster still stand; it's maybe not the most optimized build ever, but certainly entirely playable and will get him in without much muss and fuss.
As to Core-only PrCs... well, he didn't actually say "Core", he said "SRD". And in SRD there's Battle Sorcerer 6
/ Fighter 1 / Eldritch Knight X
, which is again maybe not the most optimized, but very easy to play, will give him good hands-on experience with arcane magic, and should be at least reasonable even if he messes up spell selection. Battle Sorc will improve his gish-ness and let him actually wear armor (a weakness in Eldritch Knight as-printed), and he'll still hit 9th level spells eventually.
Only... he actually wants to be useful at casting...
Seriously, battle sorcerer sucks. Less spells known = fail. Particularly as he will be the Primary Arcane Caster in the party, he is going to need MORE flexibility, not LESS. Just grab Mirror Image to make yourself practically immune to Melee, and start flinging spells. Never in your career should you ever consider getting into melee reach with ANYTHING.