If you install this pack, you can use the "official" LE scenes, for example you can remove the junk from the tunnel without 3d editors, just delete the surplus objects from Escape LE scene and recompile with xrLC.
---QUOTATION--- The ZRP patch has several such additional transition points. I suggest you download it and examine NatVac's files. ---END QUOTATION---
I think you would have benefited by heeding ERForman's advice, Llynix. You could have ripped that level changer code right out of the ZRP and spawned a level changer at the concrete, one you would have to jump up into in order to make the transition. It needs just two files in the scripts\ subdirectory, zlc.script for the level changer code and level_tasks.script for the marker, plus the call to create the LC.
You could use those two files in your mod as is and just install the level changers with a call to zlc.add_fp_level_changers(), like so:
if zlc then zlc.add_fp_level_changers() end
This adds certain level changers depending on your progress through the vanilla game, but you can easily change that to always just add that particular Cordon-to-Dark-Valley level changer. The function is safe to call multiple times as it will add the LC only once.