D.S.
Hi M.,
Consult your pediatrician first regarding his unwillingness to pee. Maybe it has something to do with his medical problem.
If there is no medical or other such issues involved, I'd just give away all his pull-ups. Then tell him no more pull-ups. Its over. Make the tone of your voice sound firm. Take him to a store like Target and go shopping and let him pick out a new potty seat, and lots of underwear (the kind with cartoons on it). This will make him feel like he is in control of the process. Make your potty & undie shopping trip really special and fun to celebrate this next step he is taking ... kind of like a right of passage.
Let him pee in his underwear - he's old enough to put on fresh underwear himself. In the potty training process, there are lots of accidents esp. in the beginning so don't get discouraged by this. When he has an accident, don't make a big deal about it. Just say "accidents happen, you'll get it right soon".
If you can, try to get him to sit on his new potty in the morning, before going to bed, and about an hour after he drinks something. And, whatever you do, don't put the pull-ups back on him ever again. When you got out, bring extra clothes and underwear for him with you. Eventually he will tire of having wet undies, and having to change his clothes. Also that potty training dvd with the bear is pretty good.
Good luck.
Diana