How to Enable Modding in Fallout 4 Even though you’ll be using the Nexus Mod Manager, you’ll still have to perform a quick tweak to Fallout 4’s game files before it will accept the mods you install. (Other games, like Skyrim, won’t require this tweak, and you can skip to the next section). First, navigate to the Fallout 4 folder in your documents directory. You’ll find it under C: Users YOURNAME Documents My Games Fallout4. Double-click the Fallout4Prefs.ini file to open it in your default text editor. It’ll open in Windows Notepad unless you’ve installed another text editor like.