Ask them nicely to take the pills OR Get a friend and a towel. Wrap your cat in the towel snugly so it can't scratch and have your friend hold it while you put the pill in its mouth. Hold your cat mouth shut and rub it throat till it swallows.
There is a product called "pill pockets" that come in all different flavors. You can purchase them at a pet store you your vet. You could also try to wrap the pill in a little piece of turkey. Another way is to grasp their mouth on both sides so it opens, put the pill inside as far back as you can, close their mouth holding their head back while rubbing their throat so they swallow it.