I read this book. I also tried the protocol. For me, to be honest, it didn't work. I hear great things from other patients though. I guess it depends on the person. I was told that if I continued on for a longer period of time it would work but I was skeptical.
In terms of gluten, if that is a trigger, you can try a product like Glutenza, that helps with absorbtion of gluten. For me, the main culprit, after trying just about every diet in the book, is dairy products and beef (MAP Infection theory of crohn's). Dairy is often difficult for anyone to digest anyway. My father, who does not have IBD, takes a substance to help him absorb lactose.
Another protocol you might try was developed by Jordan Rubin, the Garden of Life guy. Some say he is a scammer. One of his products is dirt. I'm not sure about him. He did seem to have photos showing he cured his Crohn's, so it is hard to say.
Anyway, as far as what works for me, avoiding/limiting coffee, not too much raw vegetables or fruits at once, watch out for brown bread and multigrain, no alcohol, no dairy, no beef/steak. Pretty much everything else I eat. This has been the best diet of those I have tried, but, again, everyone is different.