My three year old finally "got" potty training when I made him clean himself up after each accident. I would just stand him in the tub and let him strip off his own wet or soiled clothes and then hand him wipe after wipe until he got all the poop wiped away.
He only pooped in his pants twice after he was totally responsible for doing the cleaning. The second time it happened he cried and cried because poop was "gross".
I was doing all the cleaning up and he just stood or laid there while I cleaned and wiped...so it was never his problem.
Also, I had him pick out his own underwear, per all the advice (he had Thomas and Spiderman...and had no qualms at all about peeing or pooping on them)...I had an odd pair of undies with frogs and alligators on them, he got as a gift. Anyways...we got down to that last pair and as soon as he saw the animals on them (he LOVES animals) he said "I can't poo poo or pee on my ANIMALS!!" This happened about the same day or so as I started the new cleaning yourself routine. I raced out and found every pair of animal undies I could find.
So, animal undies or cleaning himself...don't know which...but its what worked for me.