As I remember, you have to copy it to the game's folder, name it pldecal.wad, then copy it again and name it tempdecal.wad. The make them read only so steam doesn't change them back next time you go into your options. Also in one of the subfolders is a remapped.bmp which is your current spray. I deleted that while trying to get it to work, and I'm not sure if that helped or not. I think it's really just the pic it shows you when you look in your settings, so probably just the pldecal and the tempdecal are all you need to worry about.