I've started clicker training my cats. You have to start with basic tasks. The first you teach is touch target. You take a stick, spoon, whatever and get them to touch their noses to it. You "shape" the behavior. At first you click just when they acknowledge the stick then next you click when you sniff the stick. With cats this is easy because they naturally want to scent everything. After a while you can get the cat to follow the sick around the room.
The next task is go to mat. I set out a piece of paper and again you click when they acknowledge it, click when they put a paw on the mat, then 2 paws. Eventually you get them to lay down on the mat.
After these 2 tasks the cat gets the idea that clicking means they are doing something good (because you give them a treat everytime you click) and you can shape ANYTHING. Each cat is different in how long it takes to shape a new behavior.
Between my 3 cats, 2 are coming along well, but one is doing exceptional. She just gets it and so quickly too. I'm still only on the second behavior. There are books you can read, I'm also on that clicker users group. I get most of my information from the users group, its a great resource since its specifically for cats and clickers. And a decent clicker is necessary. It has to be sharp enough for them to acknowledge it.
This method works with dogs, horses, birds, cats. etc. But cats attention span is smaller than many animals and so you have to keep the sessions short around 3-5 minutes otherwise they will get frustrated.Clicker Training For Cats