This technique has a number of premises including the understanding that acute (new) pain is helpful and protective, even though unpleasant, inasmuch as it is a warning that something is amiss (like an alarm signal) and needs to be sorted out, whereas, chronic (old) pain in general no longer serves a purpose, rather like something that is past its "sell-by date", or like an alarm which has malfunctioned and continued to ring long after the cause has been dealt with. Once chronic pain has been appropriately and thoroughly investigated medically and it has been determined that conventional medical therapy is either not available, effective or needed, then alternative means of relieving the suffering are appropriate, provided they are safe and effective.
Steven describes this process on his website. This technique does not require a formal trance or hypnotic induction though it does require deep relaxation and can be combined with other therapies.
It goes without saying that cause of a pain needs to be appropriately investigated before using these kinds of techniques to relieve the pain. The advantages of this technique include its safety, speed of onset, and remarkable effectiveness, not to mention that no drugs are involved. This technique has been effectively used in my office for a number of patients with chronic pain. Not everyone responds but there is nothing to lose but your pain.