Hi Heather! I agree with LisaMo's advice and I have some of my own.
Please don't presure your son. I am watching a friend "battle" with her three year-old son and it is painful for all involved. Your son will give up diapers when all the preparation meets his will to make it happen.
With my son, we read a lot of books about using the potty, written specifically for little boys. His favorite is "My Big Boy Potty" by Joanna Cole and Maxie Chamblis. We still read that one a year later 'cuz he likes it so much.
Another helpful hint is to let him in the bathroom with his Daddy so he can see what his Daddy is doing. If you have any friend's sons, cousins, or sibblings who are a bit older and potty trained, let him hang-out with them and see how it works. Use the peer presure to your advantage!
When my son gets into the bath he is stimulated to pee, so we would get out a special cup and he pee'd into it. Then I let him dump the pee-pee in the potty, say "bye-bye" and flush. This helped with the concept.
LisaMo was right, you need to have a sense of humor and make a game of it as much as you can. Boys are so competitive, even with themselves! Aiming at a floating Cheerio or Frut-Loop in the potty was fun for my son. When outside, we'd see how far his "stream" would reach...WOW! Thats a lot of pee-pee...can it go farther?
Rewards were important for my son. Using the potty (and washing his hands) meant an M&M. Just one, not two.
We never pressured our son, just talked/read/watched videos about it a lot. One day when he was about two and a half, he declared he was done with diapers and he never went back. Sure, he had a few accidents, at first, but we laughed them off and made light of them.
Good luck. Your son will get there!