Play as the Pope?

I've got a little bit of an offbeat question for everyone who's willing to lend an ear.

I've been thinking lately about the possibility, just for kicks, of playing as the pope. No, I don't expect it to be a serious (or particularly fulfilling) game, but I'm curious to see what would happen if the Papal States, such as they are in the game, were made playable as a normal, allowed-to-expand-and-conduct-war player. The goal would most likely be to attempt either an expansion and unification of Italy or a defense of the central portion (and other Christian bastions) against the encroachments of the Holy Roman Empire, France, Norway/Denmark, and Arabia.

So my question is twofold: first, is this conceptually possible, or is there something fundamental to the mod that won't allow for this? Second, assuming it is, what would I need to alter (other than the obvious lines to make the Papacy a playable character) to turn the Pope into a "normal" participant?

Thanks to anyone who's got ideas to share!