Well, illithid wizard is already kinda overpowered, making him a lich would not change much.
The only thing i might suggest is that you (try to, at least) add yourself a necropolitan template (to become an undead) and just mod your stats to match lich's bonuses. And don't forget, you need to be in singleplayer for DebugMode 1 to take effect; if you are joining your server via local network, it wouldn't work.