My son turned 3 back in April and is just now potty trained. I constantly praised him every time he peed on the potty (sang and did the potty dance)and just encouraged the pooping. I took away the pull ups and he would just poop in his underwear. I would allow him to use a pull up to poop for a few weeks. I explained to him that he was a big boy and he should poop in the potty, but again, I didn't make a big deal about it. I let him help me put the poop in the potty.
He would occassionally go on the potty and again (praising him each time). We even used M&Ms to bribe him. Since he was getting his pullups to it was clear he knew when he had to go, so I took the pull ups away. Now he is in underwear, with and occassional accident.
We also told him we would have a "Potty Party" when he was out of diapers and pullups to encourage him to go. The part is next month.
Hope this helps a little.