The files are included. Just take the 2 folders of vmodel and wmodel and place it in your models folder found in the materials.
Place the whitelist.cfg in the left4dead folder where the vpk can be found.
edit the vpk file. find the line with the pumpshotgun
$baseTexture "models\vmodels\Weapons\Shotgun/VPumpShotgunReference"
and replace Reference with Reference2










