You do not have to skuff into the glass. First clean any oil (from your hands, etc) off the limbs. Denatured alcohol will work. Then take 220 grit sandpaper on a block and run it up and down each limb several times. Just enough to take the edge off the finish and smooth out any little varnish bumps that may already exist. Certainly not enough to deface any decals. Then clean again with denatured alcohol and size with Titebond II or III, i.e., put on a light coat of watered down glue with a foam brush or your fingers and let it dry. Wet the snake skin until its soft and apply glue to the non scale side. Place it on the limb(s), align it properly and work out any air bubbles with your fingers. After it's dry, use the 22o sandpaper on a block again to knock off/sand the skin from the edge of the limbs. Check for any areas that may have lifted, particularly along the limb edges. Then remove the scales and varnish. Good luck. If you need to remove the skins after a few years, slide a razor blade under the skin and slide along the limb. A light sanding with 22o will make it ready for spray or hand rubbed finish. Good luck.