Karaynn Long wrote this article on how to toilet-train your cat. Apparently, "toilet-train" is to be taken literally - you can train your cat to go in the toilet (imagine never having to clean the litter box ever again!)
Watch your cat using the bathroom in the metal bowl. Count the number of feet he gets up on the toilet seat (as opposed to down in the bowl of litter). The higher the number, the luckier you are and the easier your job is going to be ...
...because next you have to teach him proper squatting posture. Catch him beginning to use the toilet as much of the time as possible and show him where his feet are supposed to go. Just lift them right out of the bowl and place them on the seat (front legs in the middle, hind legs on the outside). If he starts out with three or, heaven forbid, all four feet in the bowl, just get the front two feet out first. Praise him all over the place every time he completes the activity in this position.
http://www.karawynn.net/mishacat/toilet.html - Thanks Skully!