Storing them in beer is probably what killed them. Their skin is basically one giant mucous membrane, so they can absorb whatever they're in. Probably for the best that the snake didn't take them. If they had absorbed a lot of the beer it could be bad for him.

Get some dirt and leaves from your yard, put it in a cup or tupperware container, and either put the top on it or wrap the top in saran wrap and put holes in it. They'll crawl out otherwise. Keep the soil moist and put them in a dark, cool place. I kept a couple slugs alive for several weeks like that once.