Page 5 of the "what are you dying to learn" thread. I asked before and knew it was on here somewhere.
From a dude who can only tap one thing (this) -- It's pretty easy to do, but I have a really hard time getting something that sounds really loud and clear. Have to turn the volume way up and then I get a lot of feedback and it really magnifies any unintentional little noises you get out of the other strings.