The option "Force default models" is used to make sure you dont see any other skins than the default ones. I use it to get rid of that damn warcow. If a player use the warcow model, then I allways see the standard male soldier. On my own servers that model is not enabled.
I dont think there is a way to do what you are asking, unless someone has made a mod for it. Never seen a mod like that though.
I think you can force everyone to use the same skin by removing all skins except one, and then use this entry in the servers user.ini
[DefaultPlayer]
Name=Player
Class=BotPack.TMale1
team=0
skin=CommandoSkins.goth
Face=CommandoSkins.Grail
Voice=BotPack.VoiceMaleOne
OverrideClass=
This entry should be the only skin that is installed on the server, all players would then get this skin (or at least thats what I think)..
I realize of course that this does not do what you wanted