i'm not sure if you can set the masked colour of a texture. I'd be very glad if someone proved me wrong tho :) Oh the search feature of the forums kinda sucks, so don't give up if you've searched and not came across anything :o)
Could you not just set use 0,0,0 as your masked colour? And set the black parts to 1,1,1?
Could you not just set use 0,0,0 as your masked colour? And set the black parts to 1,1,1?