To install, double click, or place the .vpks in [YourSteamFolder]/steamapps/common/left4dead2/left 4 dead 2/addons/. You must have Left 4 Dead 2 Add-on Support installed (Steam->Library->Tools->Left 4 Dead 2 Add-on Support).

Special thanks: pappaskurtz - Zeq Macaw's right hand fix, face flex info.