I have done a version of it, hypnoanalysis. It also started as with progressive relaxation and an induction. Then we created a special place where I felt completely safe and at peace, where nothing could intrude, where I was in complete control. And I could invite anyone there, including my shrink. After it was over I was encouraged to draw the place and to use it as a place to go when things started to overwhelm me. It was helpful when there was traumatic material that needed an extra container. Now I don't really need that as much, but at the time it was useful.