I gave birth to my 4th child using hypnosis, after preparing for it with my hypnotherapist for several weeks, and I never needed so much as a Tylenol during the whole 14-hour labor. This was almost 15 yrs. ago, and at the time, it was almost unheard-of. I remember the labor nurses coming in and out of my room and whispering to each other, "I don't know what she's doing in there, but she's quiet!". What I used for a guided-imagery scenario was a beach at sunset; with coaching, I was able to visualize myself lying on a deserted beach, with a soft breeze blowing, seagulls flying around, and of course the waves, which represented my contractions: building up slowly, then mounting higher and higher until cresting, and finally washing over me with cool sprays. In this manner I went through labor, transition and birth without once losing control.......I never even broke a sweat (thanks to that ocean mist!) and delivered my 8 lb. 2 oz. son in full makeup!
So, yes, it works, and for me it was much more effective than Lamaze. Good luck in pursuing more information; this is a wonderful way to give birth, but it's still not well known, and thus underutilized.