This is probably THY seminal work that you need:
http://www.amazon.com/Interpersonal-Process-Cognitive-Therapy-Jeremy/dp/1568218583
I've been reading articles on decentering and almost all of them quote that Safran & Seagal's work.
Also, I don't know if it's valid but I think Hayes's Cognitive Defusion is the same kind of construct. You should check his work and see if it fits what you're looking for.