The way to do this of course is through the standard methods of clinical science. I also agree with you that the theory used to explain benefits from these therapies is absurd because there is no evidence for the basic premises, not to mention that it is at odds with our scientific knowledge of the body. It is simply the latest occurrence in the brief but sordid history of psychotherapy. Let us learn something from history. Now the same phenomenon is starting to be seen with EMDR, in my opinion.
Humans are notorious pattern-seeking post hoc reasoners.
The innovators found themselves doing something . . . It felt good or worked for the therapists, so they made some assumptions in order to create an ideology that would support practicing the method on others. Questionnaires taken 6 months after the treatment demonstrated relatively paltry improvements. This was the result after Callahan himself did the treatment. Unfortunately, there was a lack of a control group, but the results can be more parsimoniously explained through a combination of standard mechanisms of therapy like non-specific effects and placebo responding, and possibly the imaginal exposure component.