After a week of tricking Foreman by going to the glass door and then nabbing him by the collar to lead him to the doggy door, he finally seems to have the hang of what the doggy door is about. Today when I got home from work, he ran to the glass door and I walked past him toward the doggy door and he then ran past me and out the door. When he finished his business, he came right back in.
The next step…getting him to figure out that when he has to go, he can take himself out. At the moment, he just goes and sits by the glass door until he is desperate and will then either bark or run in my office and paw on me.