I'll not be held responsible for any injuries or suffering if anyone tries this techniques. It requires special guidance from a qualified instructor. I doubt you will find many instructors that know this technique as they are very old techniques and are only usually taught to special students with high potential, dedicated, respect teacher and self-respect, and patience.
Light an oil lamp or a candle and place it onto a table. Stand about 3 feet away from the candle in horse riding stance. Channel your Qi down to your dantian and concentrate on yourself. Thrust out your fists towards the lamp or candle for about half an hour. Practice this art every morning and evening. Once you can put out the flame you have successfully passed the first stage. Now move yourself back 8 paces and repeat the same exercise. Once you can put out the flame from this distance you will be successful. It is said that once you have accomplished this that you can hit a person without even touching them.