Also known as Engaged to the Unidentified
In order to use this mod you will need to download GCFScape to open the readme with the actual mod as well as instructions in it. Here is the download link for GCFScape[nemesis.thewavelength.net] Start up L4D2 and let the addon download. Once downloaded exit the game. Now all you need to do is go to your addons folder in L4D2 which will likely be in "C:Program Files (x86)Steamsteamappscommonleft 4 dead 2left4dead2addonsworkshop".
Look for the picture that has the thumbnail for this mod. Once you find it open the vpk with the same number as the picture. Drag the vpk into GCFScape and open the readme. From there follow the instructions provided.