You don't really need a stock for this. Other than the single line to set the prop, your only other logic is to look for the name of the prop in core.games gamedata, which it will never actually fine unless someone adds it there manually.
PHP Code:
SetEntProp(ent, Prop_Send, "m_nSkin", value);
This is all that is needed. It's the same as setting any other netprop.
@Sammy-ROCK!
SetEntityModel sets the model as the function name suggests. A model can have multiple skins (textures) in it.