How do I enable mods in my WRCG Install?

Either compile, or download a copy of WRCGUnpackager.exe from the releases
Place WRCGUnpackager.exe into the installation directory of WRCG
Launch it, and wait for it to complete.
If successful, inside of Common\Settings there should be a file called settings.cfg, open it and change Engine.UsePkg = true; to Engine.UsePkg = false;.
All done :)