This is a hard road, but sometimes you just have to wait until the kiddo is ready. However, make sure that he knows what's on the other end of the deal. My younger son despirately wanted to play on the big playground at school. Every day he would ask. I would say "I'm sorry, but the kids that play on this playground use the restroom, wear underwear, and are at least 3 years old." Every day, he would ask.....every day I would answer him the same way- "Did you use the restroom? Are you wearing underwear? Are you three?" and until he could answer all 3, he wasn't able to go to the big playground. I wasn't really in a rush to have him trained; we were renevating our house at the time and living in a hotel- I knew that transistions were hard for kids, and I only wanted to train him once (I did learn that from years of working with toddlers and preschoolers) so I didn't want to work on it until we were back home. Well, we went through quite a bit of the question/answer days as mentioned above, and then one day, he got in the car and said "Mom, you now have 2 big boys in your house. John and me. I'm not wearing diapers any more" and he didn't. He had maybe 2 more accidents, and that was it. OF course, on the bummer side of this, he still couldn't go to the big layground until he was three, but once he was, it was his favorite place in the world.
I think the whole point of the ramblings above is that potty training has to have some value to the kid, and it has to be his decision. If his favorite thing in the world is chocolate, but he gets chocolate for other things besides going potty, using the rr is not going to be any big deal; he can get chocolate later for just being the most darling son you have. If you decide to use chocolate, or candy, or stickers, or whatever his main reinforcer is (sorry, teacher talk is coming out) to give him incintive and reward him for using the RR, that is the ONLY time he gets that reinforcer until he's mastered the skill. Don't be afraid to use other people in the house to reinforce this. If you have an older child, give that child one of the younger one's reinforcers. If he asks for one, too, "Oh, sorry- John uses the restroom and wears underwear"- or use yourself if there's no siblings. But also, keep in mind that pottying is such a good place for kiddos to play the power struggle game. If he knows you will beg for it, why not make mom beg for it. But if you attach a specific reinforcer to the behavior, and then not make the situation a YOU VS. ME situation, then perhaps you will have better luck at getting the skill down more quickly.
Hope this helps- if you need anything else, please PM- I've helped kids ages 2-12 learn to used the restroom and get out of those diapers. (Some of that is training parents, too- especially the 12 year olds!
*Note: I work with kiddos with disabilities- the 12 year olds were not developmentally 12, but their 12 year old habits were hard to break sometimes!*) I'm not Potty Queen, but do have a bit of experience, and can possibly give some suggestions specific to your situation.