I used a stainless steel nail (sterile) to poke tiny holes to start unzipping for Lucky, and also for two buttons yesterday. It keeps a big oops from happening. I just lightly tap tap like a baby would, and watched for an ooze....
I think if you go real slow, taking a long time, and remembering that he's not in too big of a hurry if he can breath, you'll get him out safely by dark, and he may be happy to help, once he sees their is hope.
Use your patience and excellent judgement. Especially the patience.