I was actually considering bringing in the Turner from Lemmings 3D...
Oh, then I need to postpone the development of Lemmings, Drugs, and Rock 'n Roll instead, because that one is L3D-inspired...
In all honesty, though, I believe this could actually be done, given that you've already implemented the Splitter from L3D. The Turner would then be a Blocker that lets every second lemming through, thus sending lemmings into two different directions successively. Not a very useful skill, I guess, but technically doable.
An upvote for this: if it could make the chosen Lem start walking on the ceiling and then perform a digger skill, we have our upward digger (and, effectively, downward builder) plus the fact that this skill would be useful for so much more.
Indeed; this is precisely what I also brought up in the Downward construction vs. Upward destruction thread. But I see you've already responded there, so you probably know.
Magno Boots or Gravity Reversal could kill two birds with one stone here.