I used to run a trot line for softshells when I was a kid. I'd make some money by selling some to the locals across the tracks but I'd always keep some for us too. We'd just fry it up like we did everything else we caught, gators, frogs, fish... You get a lot of meat off a big softshell but be sure to clean all that yellow fatty stuff off! I cleaned them basically the way Longhunter described it. You can do it without cutting the shell too, but it's a pain.
Adam