More than one alpha mask. T3D L3DT

Hi,

I'm using L3DT to create a terrain and it's giving me two alpha masks. I'm assuming you can go into Photoshop and add the other masks into the 1st alpha image and then edit the mask.xml file to reflect the changes. The .xml file has the Layers as red, green, blue. What would I change to add in the new layers? In other words what do I put where it says LayerColour? Assuming of course this is how you do this?

Below the layer is blue:

<Layer>
     <LayerColour>blue</LayerColour>
          <TexList>
               <TextureFile>"C:Documents and Settingsmichael_L3DTResourcesPro 2.7.0.0Climatescommongrassgrass1-dry.jpg"</TextureFile>
          </TexList>
     </Layer>