Add faces to a model

[Hulapyk]

Hello there!

I was wondering if anyone could help me out here.

My mate and I recently downloaded a firefighter model to our server (this model: [url]http://steamcommunity.com/sharedfiles/filedetails/?id=435015039[/url] )
We found out that there is only one face which is Ted's (guy on the picture, standard HL model) and I was wondering if it was possible to add the 7 other models faces as well (which means, Vance's, Van's, Sandro's, Mike's, Joe's, Eric's and Art's, rest of the HL models)

I really hope it is possible as we need them for our RP server :)

I do have the other faces VTF and VMT files, I am just clueless how to add them.