It's very simple. You need a small hardwood block with a hole about 0.1" drilled in it, and preferrably slightly chamfered.
Remove the firing mechanism from the bolt as you already know how to do. Put the tip of the firing pin in the hole and press down. Release the safety when it seems loose. The cocking piece will stick up out of the bolt shroud at this point. Give it half a turn and it comes off the end of the firing pin. Let the pin expand sloooooooly (or it will fly all over the room) and from there on, everything sort of falls apart.