I have successfully trained my cat to use the toilet.
Here's how I did it:
- Buy a big disposable roasting pan
- Cut it to fit the bowl of your toilet
- Fill with cat litter
- Give treats when cat uses the toilet
- Lower the amount of litter every so often (could be a few days or weeks, it all depends on the cat)
- Watch the cat, when it's just about to "relieve" itself, make sure to pick it's paws up and perch on the toilet seat
- Again give treats and praise for this behavior
- Continue lowering litter amount til it's all gone
- Cut a small hole in the center of the pan
- Gradually, make the hole larger - take notice of how the cat responds to this
- Once the hole is the size of the pan you should be ready to take out out completely
At anytime your cat could rebel, and relieve itself anywhere. Don't get mad, just go back a step. It does take time and patience but in the end it's very satisfying not to have to smell cat shit and clean out a litter pan.
Below are a couple videos I took. She usually likes her privacy and won't go if people are watching.
Warning: it is a bit graphic - but for educational purposes only