CS:S & HL2 skins (VMT & VTF)

So I am trying to make custom skins for HL2 and CS:S models in garry’s mod. Ideally the way the thing would work is that you had several skins for one model (I.E the gasmask from CS:S) and you could change the skin per model (a script ish will be worked on for that). Now, where do I find the VTF/VMT for ragdolls/player models from HL2 and CS:S ? I have looked quite everywhere without any result… And I don’t know how I would skin it and so it would go in to gmod, does anyone know?

By skin I mean like TMD skin for his cars, but now for ragdolls/player models.