[k_semler]

Use a straight razor blade, as often found in exacto-knifes. You might want to dull it first though, so you don't inadvertently cut things you don't want cut. (I accidently cut through the keyboard button board when using it to remove the keyboard to do a swap, and it's a PITA to re-insert the button pad and affix the keyboard in the proper location when you've cut the button pad from the phone). What should have taken me 3min to do, took closer to 25 minutes to get everything properly aligned and put back together again.