J.L.
I did this w/my daughter, so it may work if he is still sitting down. I bought one of those potty seats that fits over a regular toliet so they can sit on it w/out falling through. This helped a lot w/getting her to poop in potty as she did not like pooping in the one that sat on the floor at all. Also I could take this in a bag when we went out and put on the public toliet and that helped too. Also on road trips where the potty stops may not be the cleanest or when you have to use a porta john. You just have to really clean bottom afterwards but I used the bleach wipes for that.