Well, he explained it, and I did it. Now give me an hour to write it up in this email
1 in you alpha file ...flatten the image
2 unlock to flattened layer...just duplicate the layer to unlock it
3 hover over the layer image in your layers window...ctrl+left click on the thumbnail
4 go to your left where the large image is in the workspace and hover over it with the mouse.
5 hit shift +ctrl +c (Copies the alpha)
6 Go back to your file with the actual paint layers
7 go to channels...at the bottom of the right dialogue channel box, hit "create new channel"
8 go to the left to the black alpha channel and hover and hit ctrl+shift+v,,,,this will past the alpha to your paint image.
9 press ctrl+d....ctrl+d again and it is now save as a dds
let me know how you do,