Airbrushing would probably still be the way to go, but I think he whould probably be wearing it when you spray it to get the details right and to avoid as much crackling of the paint as possible. I'd hit it was a little detail work like some ultrafine glitter in clear glue or poly to edge out the scales to give them a wet shiny look. It sounds time consuming, but I think it will look neat when done! Good luck!!!