I have the achievement, but I'm on a new PC and since the save files aren't cloud-based I don't have my old saves. Not sure if I'm doing it wrong or it just isn't working because I don't have any saves.
a file in the saves directory named "toorum_lives.txt". I don't remember whether it checks the contents of the file, if it does then you'll need to write "Toorum was here." in the file.