Hello, get the latest steam version of the game and then :

1. In /Doom/base/ Rename or remove the files gameresources.patch and gameresources_002.patch
2. Change "DOOMx64.exe" and "superscriptx64.dll" in the root folder with their previous version from before the patch. You can find them from the torrent linked by Artic on the Discord or I uploaded mine to Google drive : https://drive.google.com/file/d/0B3tC3CHX1XzgRGV1X0ZDT3hELWc/view?usp=sharing

This will make you go back to the 1.04 version, last version with the Level 2 skip (ledge grab) working

Also you'll notice that the autosplitter provided by livesplit doesn't work for this version so try this one instead : https://raw.githubusercontent.com/loitho/doom-autosplit/master/Doom%20-%20clean.asl