Knowing Fister, I nearly panicked the first few times I had to give him a pill. Like Phred says, the pill popper is probably the best way to give it to him, but also Jen's advise is really worth trying!

The way I did it was, "sneak" up behind him while he sits in a window, relaxed and watching the world outside, stroke him like usual, get your fingers in from side and open up, shoot the pill down his throat and close the mouth - then stroke his throat until you see him swallowing!

Good luck!