Hi
I use Photoshop 7.0 and your problem is filetypes. Photoshop doesn't recognise them, you need DXTBmp
available
herethen within DXTBmp use 'Load extended image' and navigate to the file. Then hit image/send to editor and t will open in photoshop.
Then edit it and save it as a targa file, then in DXTBmp load your edited file back in with 'Load targa with Alpha'
then 'save extended image' and you can then view it in FS9
Hope that helps