Killing someone without touching him is quite easy, silverfang. It requires a device called a gun.
As to the validity of the technique that you're referring to, I'm assuming that you found it in "Kungfu: History, Philosophy, and Technique", or "Comprehensive Asian Fighting Arts". Though killing someone without touching them may be unrealistic, the type of training that one may put their hands through does change them into very powerful weapons.
In attempting to reach a more unreasonable goal, such as wanting to kill without a touch (or in the case of Pan Qingfu, breaking a steel block with a single blow), one's actual proficiency tends to be much higher than the guy whose goal is to "hit harder". The concept of "cinnabar hands" illustrates the fact that you have to have standards in order to improve. It would be more accurate for the author to state that "the practitioner would NOT BE CONTENT with his technique until he was able to kill without a touch." Even without achieving the "kung" mentioned in the book, after 10 years of smashing grainy stuff over your hands every day for a half hour, the hands will become rough, powerful weapons.
Regarding killing someone without touching them (without a gun), I don't know if this feat is possible (though it certainly is improbable), but if it IS possible, then it can not be achieved unless someone dedicates their time and effort into making it happen. You never know how much you can achieve unless you try.
Train hard.
--Sihing Bart
