Can you throw a towel over him to subdue him? I've never tried it, but it seems to me it would be safe to let his head poke out, then close his mouth and wrap his snout with pin-striping tape or electric tape cut to 1/4 inch wide. If you don't cover his nostrils he will be OK for the 2-3 minutes the job will take. That will make you Iguana Dundee!