When you're talking glycerin, is it the vegetable stuff at the health food store, or something from taxidermy suppliers? Witch Hazel makes sense too. It always struck me that straight glycerin would attract critters to eating the leather.
As for catching we were at a neighbor's pond. We'd fish normally with poppers and deeper running swimbaits until we stirred up bubbles. Then Grandpa Ken would grab a stout cane pole rigged with gorilla braid and a big circle hook baited with a piece of shrimp and drop it in the bubbles. He set the hook hard and kept the pressure on to keep it off the bottom. As it neared the water's edge I jumped in and grabbed the tail. Then Ken whipped out a screwdriver and let the turtle snap at it. Once it has the screwdriver he jams it down through the lower jaw into the ground and I pulled hard on the tail to stretch out the neck. Then you slice the head off and toss it back in the deep, away from the hovering kids.
He hangs them in a tree by the tail (tied with a scrap of mono) to bleed, then you keep on fishing. Cutting them up wasn't nearly as big a deal as I had heard. He scalds them for a minute, which allows you to clean the slimy layer off the skin and plastron, resulting in a beautiful creamy white working area. Cut around the edges of the plastron, gently skinning it away, then sever it where it meets the shell on either side. Quarter the front legs and neck, seperating them from the shell with a flexible bladed knife. Strip the esophagus and heart lung area. This gives you room to work on the back end. Work on the vent/cloaca area like on any other animal, taking care not to puncture the small bladder, then pull it back through the pelvis and remove. Pour the rest of the guts in a bucket, put the heart in saltwater to entertain the kids, and finish quartering. Soak the quarters in brine, then skin and remove all that nasty yellow fat.
They are neat critters, amazing cranky dinosaurs covered in algae. Most of the Kentuckians I know who like turtle either noodle or jug for them. I am too fond of my fingers to noodle, and as a mom jugging takes too much time. Plus it strikes me that pond owners like to see dead snappers like sheep farmer's hate coyotes. Good vibes for potential access.
So I asked my father in law to show me his method. When it comes to biting snappers are usually obliging. We caught 2 in 15 minutes once the bubbles started, one about 8 # and the second about 15#. My kids loved the whole adventure, including the eating part. Wish I could post the pics!