Your long time mystery has been solved!
My guide for the level:
1.) Send a climber+floater over the wall.
2.) Build over the first water gap.
3.) Shortly before reaching the 2nd gap send another climber+floater over the wall.
4.) Build over the 2nd gap with the first lem using 2 builders.
5.) Make the builder a blocker
on the bridge when he is finished.
6.) The 2nd lem should turn at the blocker (
Make a save state! My emulator was able to at least
).
7.) Mine down in such a way that he beaches to the lower tunnel and is also as low as he can gets (one miner swing more and he falls out of the map) ---> he still turns at the steel. So ~ only the upper part of the miner tunnel breaches to the tunnel.
This is nearly pixel-precise! Normally mining on steel doesn't turn
here.
8.)
Make another save state! Pause exactly before the blocker and free the blocker with a miner performed by the other lem. To ease the selection: Come with your cursor slowly from the left and stop if the cross turns into a square ---> only the walker is in the selection. The 2 athletes are now safe!
9.)
Make another save state! Select a right facing lem from the crowd near the left pillar and dig. Dig a bit and then turn the digger into a right facing miner ---> this ensures they all walk to the right into the prepared miner tunnel. Pausing at a moment where the other lems in the digger pit are all on one side helps selecting the digger using the same cursor technique as before.
10.) 8/8 saved!
+ I even have a basher to spare
Make sure to use the save states or you will be in replaying hell!
The code for the 5th level was in my case (I don't know if it's always the same. This was the first time I played Lemmings on a freaking gameboy
): AAFBFHBG
Hope I could help you! But I still would suggest the DOS version for Lemmings 2 as not having the mouse is painful --- although with the ability to pause + select a skill at the same time I was able to easily perform a basher staircase
If you want to --- try out some custom Lemmings packs here! NeoLemmix and Lix provide you with enough stuff for eternity and precise controls to make excecuting solutions easy --> your only problem is actually finding the solution!
EDIT: A neat thing I found in this version: You can cancel a miner with a basher when he is about to move forward. Also if you need a visual presentation of the solution: I could
try and record a video.