Beginning at the base knuckle of the fourth finger, cut carefully along the joint while grasping the distal phalangeal and tugging just enough to allow a clean incision along the joint with the palm; holding the proximal phalangeal tightly while extending outward will aid in the separation; make sure you have adequate antiseptic solution and gauze at hand to stanch bleeding as you slide the offending band of foreign material from the severed member.
To reattach, simply reverse the removal procedure being sure to suture all severed tendons and/or nerves; for additional fingers it is advisable to have a separate set of sterile instruments to avoid potential complaints from ‘injured’ parties...
yeah real funny :)