It uses a glitch? So my WIP method was either complete trollop or a potential backroute!
Here's what I've been trying...
Make one of the first lemmings to come out a climber, and then a floater. When he gets to the ground, make sure he builds just under the squasher trap. Meanwhile, make two blockers surronding the lemmings on the second platform they walk on, the closer together the better. Then, when the lone lemming gets to the edge of the wall he is walking on (After turning around because of building directly under the wal), start building a bridge to the left. When it's big enough, bomb the blocker on the right and the lemmings will walk down the path to the left (Although your positioning of the blockers may change this). However, the main problem is getting the builder lemming to turn around, because he will either sink in the liquid or just go to the left side of the level