There are a number of factors in determining a course in this situation. My first reccommendation is to leave the dent alone. Just ignore it. Good chance it isn't worth messing up the frame, unless the bike needs a repaint. If you must do something just putty it and do the best you can in the smallest area possible. Touch up if you must. Don't drill a hole and pull it out. I don't have time to explain why any number of approaches are a waste of time. OTOH, a hydrolic pressure technique is reported to work. I may investigate this system once we're up and running at the new Vintage Cycle Studios.
Sometimes it's just best to accept the dent, and learn to love it. ;-)
Brian Baylis La Mesa, CA
Please note: message attached