[Hydra]

how do i make a custom skin, i c the option in the hosting menu to allow them but i cant get them to work, i can get the skin by using a pff tool then edit them but cant get them to work in the game. a friend says i need to make a mod for it, but then no else can see with the mod, i ask this because me and a friend saw a guy come into a server with a custom skin, we kno that the server wansnt runing a mod because we got in...
can u tell me how to do it?