If you want to study PP, start by studying Shiatsu/Tsubojutsu and other healing arts.

It is quite irresponsible to strike people and knock them out. There is no way to be certain they will get back up.
One of the things you will learn in Shiatsu is what kind of patients to not perform the technique on. They do not teach these things in the "knockout seminars". Hit someone with a heart murmer, blood clots or any other cardio pulmonary disorder the right way at the right time and thier dead. You can tell the jury you only meant to knock him out and didn't know he had a heart condition, but I doubt it would matter. Plus, there are so many people walking around with undaignosed conditions who are yet asymptomatic. Get one of these people and knock them out at a seminar and you tirn your mat into a crime scene.

Studying the healing arts is the safest way to learn and teach these things.