Potty Training Advice

My mom is aware of the potty training problems I am having with my son and she recently sent me an article explaining a new, and somewhat radical, solution. The article, “Expect potty-training success, and it will come” written by John Rosemond, discusses a program designed for older children who are not yet potty trained and may be resisting the use of the potty. Mr. Rosemond refers to a common problem known as “stool refusal” and uses this as the basis for his advice. My son does not have this problem; he simply will not use the potty at all. But despite this variation, the article does offer a possible solution for my problem.
To begin, Mr. Roesmond recommends using the child’s doctor as the authority who is demanding the use of the potty. My son, who is 3 1/2, knows what a doctor is and does and he has seen his doctor dozens of time, but I doubt that he would recognize him as an “authority.” The only authority figures in his life are myself and my husband and he hasn’t listened to either of us yet when it comes to understanding the necessity of going to the bathroom. We can certainly try using the “doctor” to motivate him, but I am not sure how successful that will be.
The next step in this process is to force the child to remain in the bathroom by himself until he has a bowel movement. In our case, I would just like him to do something on the potty without having an audience. Our problem with this aspect of the process is that my son will not stay in the bathroom by himself. But Mr. Rosemond addresses this problem and explains that if the child refuses “to stay in the bathroom, [the parents] were to gate him in.” This is what got my attention. Maybe we should put a gate on the door so I can walk away and he won’t follow. While this goes against most philosophies I have read on potty training, it may be just the solution we need. I don’t want to force my son into potty training, but he needs to learn soon. He is getting too old to keep wearing diapers and the older he gets, the harder it is going to be to teach him. I will give him a few more weeks, maybe months, to come around on his own. But if he isn’t potty trained by the time he turns 4, then we may have to put this plan into action. Then I can stop wishing he would use the potty and tell him to just do it!