I went back to mayhem 29 to look for a lose 2 solution, and I think I found one (maybe.....it needs some checking...). It wouldn't work on the SNES though because of the water.
Well, I just found it! A0;It's now confirmed:
Mayhem 29: A0;Save 78/80 (97%)
I actually found this before I ever read tseug's post. A0;It's just a coincidence that we both thought of it at the same time!
My solution requires every skill except for one blocker. A0;By far, the hardest part was getting the lemmings spaced out enough so that the leaders had time to build and block in the end. A0;It took me 20-30 tries before I got the timing right.
Here's a hint that helps you save a couple of skills along the way (highlight to read):
[highlight]
You don't need any bashers to get past the broken pillar to the left of the entrance. A0;A well-placed digger and builder will do the job.[/highlight]
More hints are available upon request.