I have a post about feeding snails to chameleons. I don't suggest using wc snails...I do second generation onwards in a clean tank to be sure that they are parasite free. I also wouldn't use slugs. Since slugs don't have shells as a defensive plan, they often are mildly toxic, noxiously slimy (ever step on one and have it "slime" you?), and I know that banana slugs at least will make your mouth go numb.
I also don't suggest ever using aquatic snails- they are FILTHY. Especially compared to terrestrial snails....much worse.
Be careful and go slow. Snails are a luxury, not a necessary prey item.