A tip I've read on another group - and it has been reported in a veterinary journal too - is to use clothes pegs

clip 2 or 3 pegs on the back of the cat's neck (scruff) - this will immobilise the cat for long enough so that you can open his mouth and pop in the pill, always remember to follow with a small syringe of water so that the pill goes down properly, as some medicines can cause damage to the oesophagus if given dry.

I have not tried this myself because luckily I've never had a cat who was impossible to pill.

But others have said it works very well.

__________________