Just picture it. No weapons in the casino right(supposed to be)? grab whatever is under your hand... you can inflict quite a bit of damage with a well aimed billiard ball.
Since the Rock-It Launcher functionality's still in, this would be easy. Just put all the balls into a list, set that list as being the ammo for something, bingo. You'd just need an appropriate first person model...
You could just have a quest script check GetItemCount [Snooker balls] every 5-10 seconds and add/remove the weapon as appropriate. You can have grenade-type weapons use ammo lists (although sometimes the GECK automatically sets their ammo use to 1, so you may need to edit it in NVEdit).
Fake edit: May as well give this a shot.
E: I don't know why I thought the Rock-It Launcher code was still in, as apparently it isn't. Oh well.
So... I wasted some time making http://www.newvegasnexus.com/downloads/file.php?id=42062 It's perhaps more baseball-themed than pool ball themed, but you can throw pool balls anyway.