If you have multiple player skins you can only have one "active" per CT or T model. You need to edit the vmt file (Valve material Table) and change the value of the $baseTexture to you skin. (Example: $baseTexture "\materials\models\player\custom_skin")
You will need to following tools.
(to quickly edit vmt and vmf files)
(To open Steams GCF Archive files)
First open GCFScape and navigate to the file counter-strike source shared.gcf
which is in steamapps. If you have steam currently running you need to click options in GCFScape and select Violate Access
before you open the file.
Once the file is opened you need to navigate to \cstrike\materials\models\player\
there will be other folders in here each one is a player model. Choose which one(s) you want the custom skin(s) to appear on. Open those folders and extract the VTM (Example: ct_gign.vtm) Place the vtm files in your counter-strike material folder "\cstrike\materials\models\player
" make sure your custom skin (vmf) is in the same folder as the vtm.
Now you open the VTFEdit and open the vtm, you will be met with a few lines of code. Look for $baseTexture
and change the path name to where your skin file is.
So the path name should be something like this. "materials\models\player\custom_skin"
Save the new file and close the program. If ive written this correctly you should have a custom skin on the selected model. If not it will still be the original or pink/black checkerboard look.