To apply the skins, go into the I3D I provided called "ApplySkins". Once in there, go to the material section in Giants Editor and head down to the first 3 dots on the first line. Click those then choose your skin.
Then once all done save then import it back into the main i3d and do the code for it. Pretty simple. I shouldn't have to explain it all.
I've provided other skins in the Skins folder if you'd like to apply them yourself. 
I've added 10 skins already into the configs.