I have had this biting problem ever since high school. I'm 65 now so I've been at it a long time. I've searched the web for years for a cure, but never found one. Then, just by fate I suppose, during a general disscussion about phycology my friend told me about a book written by Eckhart Tolle "The POwer of Now". Kind of deep, but interesting. I worked with his suggestions and without noticing it my cheek biting stopped. It has only been a few weeks, but that, for me is all the success I need to that: 1) I can quit. and 2) Tolle is spot on with his thinking. For me anyway.
The book isn't very expensive. Actually it's free in a pdf format on the internet.
Your post is pretty old but I hope this will help someone else like it helped me.