Open (or create, if missing) Fallout4Custom.ini with your favourite text editor (we use Notepad++). How to enable modding. Gophers Video explaining how to enable mod support. If the file is fomod ready, press the Add new button: In the dialogue, browse to the archive and double click it. This will create a fomod, that is saved in your Fallout 3/fomm/mods folder. Installing a .FOMOD file. Navigate to your Fallout 4 Folder at the following location "Documents\My Games\Fallout4" Within this folder you'll find a number of .ini files. You should read the readme for instructions before proceeding. Once FOMM is installed all you have to do to install a .FOMOD file is double click the .FOMOD file in its directory, go to package manager in FOMM and click the mods name on the list and the click activate. Fallout Mod Manager is available on the nexus. Fallout Mod Manager is a tool used to manage your load order and install mods correctly. How To Enable Fallout 4 Mods. The mod can be activated by pressing the Activate button as above.