Hi Katrina,
Actually if you got a couple just after they molted so they are still soft I would be very surprised if they didn't try to eat them.
Even the large females at work still feed on waxworms and crickets if I put them into the tank. (They actually search the surface of the tank and hoover up any crickets the frogs miss and fall into the water.
I would expect them to eat some of the slugs species but I do not know which species have extra nasty secretions so it would be guess work as to which species they would accept.

Ed