Well the [http://www.ifixit.com/Teardown/iPhone-1st-Generation/599/1|teardown] is rather vague on that but it gives a general idea on how to go about doing it, removing the antenna plate first, I've heard the most effective way to go is using some good quality nonmetal [http://www.ifixit.com/Tools#0-Spudgers|spudgers] and making sure to apply pressure evenly, so as not to bend any part.