Well, finally a post that got me to register!
Ohio Department of Natural Resources used to have a webpage showing how to clean a snapping turtle. I just did a quick check there and didn't find it, but perhaps it is still there somewhere. I've never done one personally, so I can't offer you any tips.
A couple of things about snapping turtles, though:
The softshelled ones are a different species. Oddly enough they're called softshelled turtles... They will certainly bite, though.
Speaking generally, turtles have evolved a life history that allows virtually all of the eggs/babies to get eaten as long as the few that survive to breeding age live for a very long time. And they do, as adults have few predators and may reproduce for decades. Harvesting by humans (not to mention road mortality) reverses this- we take the adults. Virtually every study ever done shows that this is not sustainable. There isn't a surplus of adults like there is with deer! You could eat all the turtle eggs you want without having much impact but eating the adults eventually causes the population to decline.
Also, snapping turtles eat fish, amongst other things, and like many predators they bioaccumulate toxins such as methyl mercury, mirex, etc. You're probably aware that younger, smaller fish are safer to eat than older, larger fish which have had more time to accumulate these things in their flesh. Now extrapolate this to a predator that also scavenges lots of dead things and lives for decades building up toxins. Not my idea of a great meal.
Cheers,
Jeff Hathaway