The modules contained in this directory are unsupported but should work fine :)
To include extramodules in your GFSGL build run GFSBuilder with the -en extramodules option. For instance: $ ./build -en extramodules
To install extramodules after installation or something similar you can build a GMod installation package (gmi). Run ./Buildpkg Then run "gfsgl --instmod /path/to/file" to install ExtraModules. For instance: gfsgl --instmod ./ExtraModules.gmi