M.K.
If you're going for a short haircut, it's MUCH easier with hair clippers. Amazon has a bunch you can choose from. Look at the attachment numbers they come with. We got a set that comes with a #8 attachment, which is really nice and long so I can cut even the hair on top wtih that and it's not anything like a buzz cut. If you can cut his dad's hair (or pretend to) first that might help him get used to the sound of the clippers, but they never bothered our son.
I agree with the other posters on having a camera ready, and having a distraction source is good too to keep their head still. Good luck!