The two methods that work best for me:
Plan A - Clean an area of glass above the water line to remove all salt creep. Pull a Snail from the bag and hold it near the glass above the water line until it attaches to the glass. Repeat for all of the Snails. Eventually the Snails will begin to crawl into the water and will self acclimate as they go. If any of the Snails refuse to attach to the glass I proceed with Plan B.
Plan B - Float an empty bowl in the tank and let it warm up to the water temp. Discard all of the water in the bag and set the Snails in the empty bowl. The Snails will expell more water, pour it out of the bowl occationally. After a couple of hours and after all of the Snails are closed up tight sink the bowl and let the Snails self-acclimate.