Toilet training a cat is not only possible, it is actually fairly easy for those who have the time to do it. Ideally, you would have more than one bathroom in the house, so that one toilet could be used exclusively for training.
The best way to train a cat to use the toilet is to start with the litter box next to the toilet. As the cat gets used to going in the box, gradually raise the box using boards, bricks, or whatever you have on hand, until the box is level with the seat of the toilet.
Once you have the box level with the toilet and the cat is still using it (hopefully), put the box on the lowered toilet seat. The cat will eventually get used to jumping on the toilet to go. Once your furry friend knows to get on the toilet to go, remove the box and put a piece of caging between the toilet and the seat. Since cats are creatures of habit, the caging (fine enough mesh not to hurt his feet, but large enough for the waste to go through) should not hinder his going where he is accustomed to going. When enough time has passed for him to get used to going on the toilet without the box, you can remove the caging altogether. The cat SHOULD be so used to going while on the toilet that he goes there every time, provided the door is kept open for him. As for teaching him to flush, I can only speculate!