It's possible, but you'll have to edit the model and skin to do it.
Open the model, and re-apply the whole skin with alpha blending. Export the model to w3d and put it with the other models. Then open the skin file and add an alpha channel to the skin. Set the entire alpha channel to very dark grey. You can add some variations in the greyness, but remember that a bright alpha means the model will be more visible there. Save the skin, put it with the skins.
Then run the game and enjoy.
