Hi J.,
I have just finished going through the exact same thing with my son. We started potty training when he was three and we did everything! Every method in the book, but he had no interest. Finally, the stickers on a calender worked to get him to pee in the toilet, but only for about two months then he relapsed. I had even put a jar of M&Ms over the toilet so he could see the treat he would get, but that wasn't enough. Then the lollipop incentive, new toy incentive, letting him run around naked, having him wear pants with now pull-up, etc. He wouldn't use a baby toilet or the removable seat that comes with it and he also was scared to sit on the toilet which made getting him to poop rather difficult. I'm sure you have heard the saying, "he'll do it when he's ready, it will just click and he's doing it". I know I grew tired of that one. To apply more pressure he needed to go to pre-school and, of course, he had to be potty-trained. We got through with some luck on that one, he would wear his pull-up and never pooped during school time. Also by that time he had mastered peeing in the toilet.
Anyway, he is now 4 1/2 and is just now pooping in the toilet. He still is scared about sitting on the toilet so he stands to poop -don't ask me how he does this, but he hits the toilet every time. He won't tell me when he goes, only afterwards to show me and to be wiped. When I can catch him pooping into the toilet I hold him up on the seat. He lifts the seat to do this so I have to make sure that is always clean, but he is finally doing it. I probably hindered his potty training by getting frustrated with him. What I did end up doing is getting underwear that he chose (not me) and let him wear them until he had an accident then he went back into the diaper all the time making a big deal about how the underwear were his "big boy pants" and the diapers were for little boys. When he would use the potty right then he was rewarded by going back into the underwear. Some will say that is sent mixed messages, but you have to explain the difference between the underwear and the diapers (pull-ups) and make a big deal over his wearing the big boy pants. He also soon realized that one was more comfortable than the other.
When it came to the pooping, I hate to say it, but we just had to wait until he was ready. For my son, it felt like we went through two rounds of potty training, but he finally did it and it only took us a year and a half. I did get the entire family involved and had him call the grandmas and aunt to announce that he pooped on the potty so he could get even more praise, of course now he announces it to everyone on the street! Small price to pay for toilet training.
Sorry if I ramble, in the end it took time & patience. I hate to be the one to say it. It is almost like there is a block in their brain about using the toilet and then one day they wake up and it's not there. My son has gone almost two months now without any accidents, but I can't say what it was that I may have done to speed it along. I think he just decided when the time was right, although, it would have been nice it he had decided to use the toilet to poop and pee at the same time. Just be supportive and obnoxiously praising when he uses the toilet and get the family and friends involved, that did seem to help.
Hope this helps. At least know that you are not alone and boys are a strange creature unto themselves.
N.