Lightmap using greyscale textures

Hi everybody!

I'm trying to use a system of lightmaps on my model, I already know how to setup the multi-textures etc. I'm only asking if there is a way to use greyscale images as lightmaps. When I use rgb images it all works fine, but when I use greyscale images this images are ignored. I read in the references that "greyscale will be sent back as Alpha8", but is there a way to load them as color maps?