I have a three year old (will be four in January) who is doing a very similar thing. We have him in a well-respected preschool with a great teacher three mornings a week, and when he started messing up his pants at preschool, the teacher wasn't mean about it. . . BUT she suggested withholding the computer time he enjoys (he loves to play on the computer) unless he could keep his pants clean.
He's doing better at preschool where she is enforcing this with my permission, but he is still pretty bad about it at home. . . we're trying not to pressure him. He also loves Hot Wheels cars, so for each day he keeps his pants clean, he gets a Hot Wheels car from us. That helps, but he still only wants to do what he wants to do.
home improvement