Instructions
Confine the cat in a single room with floors that are easy to clean when you have to leave her until she is litter-box trained. Put her food and water at one end of the room and a clean litter box the other end.
Place the litter box in an area that gives the cat some privacy, but is also easily accessible. Many cats like to paw the area around the little box before using it. If the floor under the box is smooth, consider placing a small carpet under the box.
Choose a high-quality, small-grain litter to put into the box. Most cats prefer a fine-grain litter because it has a softer feel. If the cat is used to going to the bathroom outside, or uses your house plants as a litter box, mix a small amount of potting soil into the litter until he gets used to using the box.
Fill the litter box approximately 2 inches full with litter. When going to the bathroom outside, most cats choose an area that has a small amount of loose dirt they can scratch in, but they do not choose a section of the ground that is so loose they sink in it when they go to the bathroom.
Clean the litter box on a regular basis. Scoop the feces out daily and change the litter at least 2 or 3 times each week. If the litter box gets dirty, the cat may choose to go to the bathroom outside of the box.
Encourage your cat to use the litter box by praising her when you see her use it. Punishing a cat for going to the bathroom outside of the litter box does not work. Taking the cat to the litter box if she goes on the floor also does not work because the cat learns to associate the litter box with punishment.
How to Litter Train a Grown Cat
There is really no such thing as litter training a cat, in the way that you would house-train a dog. By the time you get a cat, he has usually learned to use a little box by watching his mother. If you get a cat that has never been exposed to a litter box, provide a litter box that he feels is acceptable to use.