Portable DVD player in his lap or some hand held game system such as leapster? I used to have to hold my son upside down in front of the salon and have them buzz his hair. We bought scissors and clippers and started doing it at home....little by little and doing Daddy's hair too. For a while both my husband and my son looked goofy as all get out, but I learned how to do it better and my son finally got to where it does not bother his so much.

I actually found a pair of clippers that are very quiet and very little vibration. Costly but it does help. He will not let me anywhere near him with scissors. I honestly think it has desensitized him some. He will actually let people rub/touch his head and actually asks me to rub his head. It is a brief rub but I was excited when he started asking me and he will let me know when to stop. lol I have short hair and my hair dresser uses clippers on the back of my hair and I took him to watch a few times. I think this help him to see that they won't hurt.

We found that running water to limit the sound of the clippers or to put a favorite treat in front of the barber's area and give it to them after works...give them plenty of time...many visits to let them get familiar with it all to gain trust...we have also done this for dental visits!!

My kids wouldn't use the clipper, and I had to have them sit on my lap and keep them fairly still for scissors until they were 7 or 8. My son only started letting them use clippers on him without a major fuss when he turned 11 or 12. My daughter still won't let them use clippers anywhere near her. She even shies when someone uses one a seat or two from her.

I use scissors as well, when I'm the one cutting his hair. He has always screamed like he's dying when he gets his hair cut with clippers! I did learn of a couple of exceptions, and I can't explain why they work, but since they do I'll list them here.
A) I take him to a barbershop run entirely by Asian women, and he lets them do his hair! I discovered this in New York when he was 2, because they had one right outside the Army base. We moved to the Florida Keys and I had to go back to cutting his hair with the scissors again. Then I found one here in Killeen (right off the Army base too), and he does great! I think it's because they are very patient with him, and treat him like he's a precious baby. They never say "you're a big boy, act like it!" lol
B) His Dad is able to cut his hair with a very small clipper (it's a beard trimmer), and he does great! I think, it's because it's so much quieter, and has a much less vibration than a regular sized trimmer.
I hope this helps a little. :)