Typically I would judiciously use an apprpriate sized easy-out or a coping chisel. the care used is governed by the fragility of the aluminum crank arm. Minor damage to the threads can be repaired by chasing them with either a 22mmX1 bottoming tap, Bicycle Research chaser, or modified crank puller for chasing the threads.
Happy Trails
john strizek
sacramento, california
USA