There wasn't really much to performing the bug in general from what I remember. I remember that I deleted my save at the very next save point after Willow leaves you because I realised just how many things I'd missed. Afterwards I used the corrupt save loader and it reverted to the room right after you retrieve Umbra from her cage. I mistakenly walked to the left, which caused the game to get stuck on a blank screen where I couldn't do anything. I understand the last part of it probably isn't important due to being a bug caused by a bug, but I just thought I'd mention it anyway.
I believe this glitch is caused by the save loader! I haven't tested it 100% since it's a bit difficult to recreate but jumping between v0.6-v0.7 using the save loader is a bit glitchy given I altered how saving works between those updates. I'm going to try and release a chapter selector or something next update that will help with corrupt save files