My father suffered from this pretty badly for quite a while.... happily however, he now seems pain-free through conventional tegretol.
What I have heard regarding acupuncture is that it is difficult to get any objective evidence of its efficacy, and I would have thought that it would not have been particularly useful with TGN in particular, since the bouts of pain are episodic and unpredictable, unless you have an acupuncturist on call 24/7 ;)