To find your save files, navigate to the following directory:
The folder will look something like this:


As you can see, the files are numbered by the save slot they contain data for. We will need to edit both the SaveSlot and the ProgressionSlot save files for whichever slot we need to make compatible.

NOTE: You'll need to follow the following steps for both the SaveSlot and ProgressionSlot files for the slot you need to make compatible.

First and foremost, backup each of the saves you're going to edit.

After that is done, open each save file with a hex editor (I use HxD), and search for the following hex string:


Now focus on the 4 bytes after the found hex string:






Replace them with:






Now save the edited files.

Now, launch the game and try to load your saves. If Steam complains about cloud save mismatch, choose local (which will be the edited save files).

If the saves don't work, make sure you replaced the hex strings correctly.