We gave up on trying to potty train him to have a bowel movement on the toilet because of his resistance. He would still resist defecating even in pull-ups, and would often resort to running around in circles when he felt the urge until the urge stopped. We probably could have achieved this goal earlier, but we found ourselves relaxing our efforts often when improvement started and immediately losing ground. It's tough to stay the course. My advice for other parents embarking upon the treatment would be to never relax the treatment until after the problem is a dim memory.
Parental consistency is the key.
Even now that's the greatest challenge, since I think we need to continue to treat our little boy for several months before we're out of the woods completely. It's a tough problem that drove us to anxiety and despair, but which I now know can be treated. BTW, thanks to Dr. Stoll for dealing with this problem with an article. We searched the net pretty thoroughly, found some information that was useful, but not the advice about combining metameucil with mineral oil. And we had tried mineral oil alone unsuccessfuly.