I have over 50 assassin snails breeding in my RCS tank. So after cleaning the plant to remove what I'm able to remove, I put the plant in with the assassins. If I miss any eggs, it's not a big problem because I have more assassins in my other tanks.
Vicki—Rena Filstar pimp #142 (four XP4s/three XP2s/one XP1) • Eheim pimp #301 (Pro II 2128) • Victor pimp #27 (VTS-253B-320)
Use alum (in the spice aisle at the grocery store). I use a couple of teaspoons to a half gallon of water, you can google 'alum dip for plants' to get exact amounts to be used. For snail eggs let plants sit for 3 days. I do a really good rinse after that and put in dechlorinated water. I do that for 3-4 days, the rinse and dechlorinate that is (I like to do about a week quarantine on plants I know have snails or critters).
For just snails, not eggs, you can sprinkle alum in there and watch them retreat and die within just a few minutes. I've done this with many different kinds of plants. If they are tough plants I just do a bleach dip but since what most I get in is moss and floaters for the shrimp, the alum is good but not as harmful to the plant. I DO recommend stirring your plants around every now and again while they sit in the alum dip. If it's floaters or something with dense roots the snails can hide and it won't get to them as well.