I'm afraid you're asking for too much CP. I don't believe there are many people here who can or are in the mood of writing a script for you. That's point one. Two, you'll need to think of a good unit roster for them, traits etc. Even though that is the "easy" part. Three, you need to specify the coordinates were you want the army to be spawned. When all this is ok, you'll run the script and get your general.

But the most important thing, something you seem to utterly neglect, is that giving a stack to the AI will almost surely either result in the army wondering aimlessly without doing anything, or simply sit there eternally until someone decides to take him out of the way. Say you enable Hannibal. Big deal, you think he'll actually go and kick Roman ass? Highly unlikely, if you ask me. He'll probably either sit there, or try and walk back (in reverse Hannibal style) to Africa through northern Italy and Spain.

My suggestion: Keep things as they are, don't try to re-create history but create your own. Don't bother with too much scripting and messing around, because this causes weird problems which can result in CTDs in the worst case. Plus, "gifting" a full-stack, several thousand mnai worth an upkeep army to the AI is probably going plunge them into bankrupty.

Maion