under the fallout 3.esm in the geck, goto gameplay, settings, search for 'actionpoints' there should be a 'fAVDactionpointsbase' with value 65, change that to whatever you want...
Won't that just change his base action points? It's hardly unlimited.
And besides, the only real way to come close to unlimited is to use God Mode. That said, I'd play a mod that boosted the amount. I've always wanted to kill 5 people in VATs.