Okay. Here is what you need to do:
Go to the dollar store or something. Buy 6 or 8 cheap plastic toys (all different).
Put one of these toys on a high shelf, where your son can see it but not reach it.
When he asks for it, say, very lightly and cheerfully, "Oh yes, that's the toy I bought you for when you go potty." If he says he wants it right away, just continue to keep it light and friendly, "Well, it's a potty toy. So as soon as you go, it's all yours." Do NOT take a grand, important tone about it (e.g., "You can ONLY have this if you use the potty"). The point is to make the reward seem big and the task seem small.
If the toy is appealing enough, he'll get over his potty resistance. As soon as he "produces" anything, he gets the toy right away. And when that happens, another toy, up on the shelf.
The point is to rewire his attitude toward the potty, and honestly, that takes bribery. Once he's had a series of successes, you can start ratcheting down the rewards -- a skittle, an m&m, then maybe a grape. He'll be trained w/in a month.