Quick, someone dig up hangtimes cat threads! Sorry to hear that though, really sucks. My cat is almost to damn lazy to use the cat box, much less chew on stuff.
This little tid bit wont keep it from gnawing on things, but it sure gets the dang cat hauling arse toward the sound of the shaking bag..
I call it "kitty crack" I forget exactly what its called, but all it is is hard cat treats in a bag.