LUA driven AI would be really nice to have, but to me at least, such a thing would be unrealistically tough.
I doubt it's done since I don't see posts in the forum from people saying they've improved the AI any.
I am suspecting LUA driven AI means to code the AI in LUA (very C like scripting language) and make it actually work.
Right now, all the AI I've seen is in a file called g_ai.c, and judging by the function names, the main AI is handled by AI_ActorThink().
Well, anyway, I'm just stating things is a different way if anything you read was unclear... But since I don't actually know anything about this, maybe it's a bad idea for me to answer...