Regular "earthworms" and not composting worms or red wigglers will do fine. You can also try pinky parts.....legs and such that have been scented with fish to see if they'll go over to eating pinks. Also Northwesterns (T.ordinoides) are well known slug eaters, so you might want to try them or try the canned snails that various reptile food manufacturers are selling. You can also try finely diced fish, like trout or another thiaminase free fish, so you don't have to be running out getting guppies all the time. If you do use diced fish, it's best to supplement it as well. Some times though, there's nothing like a flopping guppy to get a problem garter to eat.
Good luck....Roy
PS...You'll have to post some pics when you get it.
