Ow. Do something else to distract yourself, maybe twiddling with your fingers or something... Bad habits are really hard to get over. If you can last at least 4 days without pulling them, you wont do that any more.
Try clipping your fingernails and listening to hypnosis for addiction. Hypnosis really just relaxes you and retrains you’re brain to stop the addiction. Check out my Blog at http://haireyelashcure.blogspot.com/ for more info and the download for the track.