I did this many years ago w/ two older kittens & it was easy! This is the exact method I and my roommate at the time followed:
http://www.karawynn.net/mishacat/toilet.html There was no plastic wrap in the toilet, just a metal bowl that was easy to lift out and put back in when we used the toilet ourselves.
NOW, I will say the following: Neither cat took to it 100%, so we did eventually give it up. The male cat had no problem squatting on the seat & peeing in the toilet, but he HATED pooping in the toilet. He had a v high need to dig before pooping & he couldn't really dig in the water. The female cat never did master the squat; she always put her hind feet back into the metal bowl, even after we lifted them out. She was half Manx, so it may have been the lack of tail for balance, idk. At any rate, we still kept it up w/ just an empty metal bowl in the toilet, no big deal, the male could still "dig", female could keep her feet down, dump and flush. Easier than cleaning a litter box. UNTIL we discovered that the female was pooping behind the tub. Well, then we had to stop.
I would absolutely try it were I you. If it doesn't work, well, you tried. If it does, awesome! The male cat would still, for years afterward, on occasion, if the toilet lid was up, he'd pee in the toilet, lol!