I followed the directions on Sheldon Brown's page, and found it safe and easy. (Dig for the url, if you haven't already read it.)
I was surprised how easy, and glad I didn't pay to have it done.
You can align to within a mm accuracy, with gentle pressure, using a yard of 2 by 4, a stool, and a piece of black thread. (String is far too fat to allow accuracy.)
It's nowhere near as violent as you imagine: Roll y'sleeves up lad!
