Training Your Cat - DOWN
Cats have been getting away without being trained for years because many people assume they're not trainable. But one look at the big cats at the circus, or the cats that star in television and movies, should convince you that not only can cats be trained, but that they can learn an astounding repertoire of behaviors. You won't need a whip and a chair to train your house cat, but you will need lots of tasty treats and ideally, a clicker training device (available at most pet supply stores).
For treats, you can use tiny morsels of his favorite meat, specially made commercial cat treats, or just a can of his favorite wet food along with a spoon to dole it out on. If you don't have a clicker, you can make a click sound with a ball point pen clicking or by clucking your tongue---all you're going for is a distinctive abrupt sound your cat seldom or never hears otherwise.
To teach your cat to consider the clicker sound a reward, make the click sound then immediately give your cat a treat. Do this many times, perhaps 20 to even 50 or so. The click signifies a treat is coming, so you know your cat has made the connection when he runs toward you at the sound of the click. This will be your way of instantly telling your cat, "Yes, that's it!"exactly as he does the right thing. It's a way of precisely identifying for him just what you're rewarding him for doing.
Once he's trained to the click, you can proceed to train him to lie down on command. The easiest way to teach the down is with a dollop of wet food on a long handled spoon.
Place your cat on a table and hold the food on the spoon in front of him. Move the food down and forward, but hold your hand over his shoulder area so he can't walk forward for it. Gently guide his body downward toward the food. At first, click and reward him for just moving his head and neck toward it. But gradually require him to go a bit lower and lower before clicking and rewarding him.
Eventually you'll need to hold the spoon lower than the level of the table (that's why this is easier to teach on a raised surface than it is on the floor---that, and your back). By this time he'll need to be lying all the way down to reach it.
Continue to practice, and once he's doing this reliably, introduce a cue word: "Down!" Say this each time before moving the spoon downward, so that he associates it with the action.
Once he is downing reliably, remove the food from the spoon and continue, still using the now empty spoon as a lure but rewarding him from your other hand when he lies down.
Next, get rid of the spoon and just use your now empty hand to signal him. You will now have both a hand signal and voice cue to tell him to lie down.
Continue to practice and reward him. If you want you can reward him only some times, but he is a cat, and he won't tolerate working for a bad pay out for long! So keep it rich!
You can build on this behavior by requiring him to stay until released, or teaching another trick such as roll over.