Modifying skins from Custom models in UT2k3

[DJ Viper]

I'm quite new to all this and have previously just downloaded any models or skins I wanted from Skin City.
However I want to try and create a skin for one of the models I've downloaded (Soria UT2k3), but can't seem to find any way of doing this. I've tried UnReal Ed and Upaint... but I guess I'm doing something wrong.
I was hoping to be able to use Photoshop to create the actual skin

Can anyone help?

Many thanx

D.