Actually just make a square texture for the EyeWhite material and just make it the eye white with veins and no iris and you're done! Easy enough to do. I edited an existing texture removing the iris and replacing it with cloned portions of the existing eyewhite. Resaved it and applied it to the EyeWhite material zone. Viola! Eye White all the way around and the original texture still shows Iris on the Iris group.