Having been the proud owner of many a cat, in my opinion the best way to give a cat medication is to have it in a form like a paste, not a pill. The cat will not like it at all if you try and put it in its mouth, but you can get smarter and simply blot it on its hair. If the cat is able to move, it will undoubtedly clean itself as soon as possible by licking the medication off its hair; so the cat takes medication!

Do not forget to restrain the cat in a safe place (maybe a big cardboard box) after you put the medication on its hair, otherwise it will likely spread the medication all around your house. And ask you veterinary for permission before doing this - I'm not sure this way is OK for every possible cat medication out there.