I've just read an old thread on this subject so here's an update.
Cranial Osteopathy can only be practiced by qualified and registered Osteopaths. They have a four year training which includes orthodox medicine and are legally recognised. It is a criminal offence to call yourself an Osteopath if you are not registered with the General Osteopathic Council which is a Statutory body.
CO is generally, but not always, an effective treatment for infant colic. It is also useful for babies who have experienced birth trauma.
It is always safe and very gentle.
There is some scientific evidence for its effectiveness but this is limited mostly because the profession is small and underfunded.