Add two player mode for Left 4 Dead PC with multiple controller support.
To install place cfg files into the cfg folder in your steam copy on Left 4 Dead 2. (Steam\SteamApps\common\Left 4 Dead 2\left4dead2\cfg)
While playing a locally hosted game of L4D2, go into the developer console (`) and type: "exec splitscreen_liam_'controller'". This will put reload the map and you'll have splitscreen with that controllers support.