i think you just have to do the texture and foilage separately. or possibly edit the mesh from the foilage to have a plane underneath and have your texture on that plane.
Aye, I think your right. But I found a reasonable solution. Paint your texture-mask however your prefer, then export the texturemask as a TGA, then in the vertexPaint tool, import the texture-mask as vertex colors. You can then use the foliage tool’s vertcolor masking option to put the foliage only in the masked areas mask.