You will need:
DXTbmp (Download at bottom)
Some type of Paint program to skin.
DotHalo or some other Bitmap extraction program.
Alright. First open dothalo and your map. Choose a Bitmap, the Raw editor should pop-up (if it doesn't window>Raw editor) There should be two buttons,extract bitmap and inject bitmap. Press extract and save it somewhere.

Now open DXTbmp and open your saved bitmap(it should have the .DDS
extension) now press, file>save-as. and save it in 24 bit bmp image. It's now converted into a windows bitmap image.

Open your paint program and skin as needed.
Once done with skinning open DXTbmp again and open your skinned bitmap.
File>save-as>DDS Texture. Now save the bitmap in either DXT 1,DXT 3 or DXT 5. You must inject the bitmap in the format it was when you extracted.Ex:If I extracted bitmap in DXT 1 I must inject in DXT 1.

Now go back in dothalo and find the bitmap again. Now press Inject. If it won't let you inject its probably in the wrong format, open that bitmap in
DXTbmp and save it in another format between DXT 1 DXT 3 or DXT 5.

Done. You know how to skin without photoshop or the Gimp and their DDS plugins now.