Today we went back to the speech therapist to learn what to do with the IMT device. She had a student observing, and the student ended up being quite helpful as she had just had a class on VCD.
We decided that we could do the training without officially measuring his PI Max. We just had him find a level on the trainer at which he had to expend a little effort, but could almost do the abdominal breathing without tensing up. They had him lie on his back with a book on his belly and first practice abdominal breathing lifting the book. Then they had him breathe through the training device and still do the same thing — concentrate on lifting the book as he inhales, and also trying not to tense up. He only needs to do this for 3-5 minutes per day. When it gets easy, he should increase the threshold on the training device a little bit to make it more challenging.
It seemed like a productive visit, and Monkey seems quite interested in doing the training.