Two words "Prussic Hitch".
http://www.utas.edu.au/docs/climbing...s/prussic.html

http://images.ebsco.com/pob/summit/c...safetyline.pdf


I use this system. It works perfectly.

I do hope you guys who don't use a harness will start using them. There are systems that are very easy (once you learn how they work) and that never allow you to be unattached at any time. Adopt an attitude that your harness is at least as important as your bow or gun. It may seem like overkill to you, but it is your life we are talking about. So go ahead and overkill here.