Did this ever turn up? Frank Cifaldi claims that it was probably in a box of Acclaim prototypes that was stolen during shipment. I once had a scan of it from NP magazine, but I don't know where it is now. Appearently it was supposed to be similar to The Lost Vikings (Puzzle/platformer).
Recently Angry Video Game Nerd made an episode about Mary Kate & Ashley game: If South Park game was intended to be like this, it was a good thing they cancelled it. A crappy South Park game less.