On this website, look for unren, copy to this game main folder, doesn't need to be in the folder marked game, click on unren, pick option 6 force enable rollback.
I can verify it works, but sometimes can go further back than you want, I have been using it for months for F5 quick save and F9 quick load options.
I also recommend toggle quick menu, also on this site, for games that don't let you have the quick menu, or have the auto button, if you are like me and do not want to break your mouse/spacebar buttons, but this one does need to go into the game folder.