Oh, this is one I know a lot about. I went through it with Jack, and am now going through it with Tom. I find that different things work at different times, so it's a matter of just trying things until you have some luck. Sometimes toys work. Sometimes blowing rasperries on his belly works - he laughs and then will lie still for just long enough. Other times I get Jack to stand there and keep Tom occupied. Some other suggestions I've heard have been a sticker on the hand (although some babies will eat them!!), and a change table with straps to keep them still.

Good luck with it. I hope it gets easier for you soon. I have learnt to be the quickest nappy changer out LOL!!