I did a course in the Mongan Method of hypnobirthing with ds1 and had a lovely, calm, "textbook" homebirth. I never told my mw's that I had done the hypnobirthing course but they were so hands off and lovely anyway.
I never managed the full visualisation and "hypno" bit as back then I wasn't very good at unwinding my mind but the explanation of what my body would be doing, when and why (uterine contractions/surges, flowing of blood, hormones) etc.. took the mystery out of birth and gave me confidence that my body and my baby would know what it was doing. I used the breathing exercises to manage the "pain", and in the last 60-90 mins I had G&A due to high blood pressure (so it was that or transfer to hospital).
I listened to the rainbow sounds cd every night at bedtime and fell asleep to it, but sleep is the ultimate relaxed/hypno state! Anyway I put the cd on during labour, contracting every 2-3 minutes, and fell asleep for an hour so I was definitely conditioned to it! I still can't tell you what is on the cd beyond the intro music!
I definitely believe there is some truth in fear causes pain as i was managing perfectly fine until the mw turned up, i turned out to be further along than I thought and realised DH was not going to make the birth so I panicked a bit then but gave myself a mental talking to as panicking would only slow the birth down and got on with it 
I am expecting dc2 now and will do a refresher course.
Anyone considering a homebirth - you can start at home and if you change your mind transfer to hospital WITH your midwife all the way if you don't like it at any point, but you can't go to hospital, change your mind and bring a mw home with you! 