IF there aren't any out there (I'm not certain), I would recommend masking carefully and painting or get some of the testor's white decal paper (make sure to get the white, not the clear), spray on a couple coats of the decal bonder and cut to your desired size. When using the clear with printed on stuff I custom-made, I found I had to use two decals (one right over the other, which was actually a LOT easier than it sounds, just push it around with a toothpick until the words line up) to get the opacity I desired (at suggestion from Mr. Skinner). You may need two layers if you use the decal paper, I'm not sure though as I haven't used the white background one yet.
Groot