The original campaign uses RSH files for the textures (hence why some of the details are slightly different colours etc - it doesn't use the .teamcolour and the WTP like the skirmish does)
In brief, to make the Marines in the DoW Campaign use an alternate colour scheme you need to do the following (using the
Texture Tool):
Extract all of the WTP files from the "w40k\w40k-textureshared-full.sga" file using an SGA tool of your choice (SpookyRAT, Corsix's SGA Reader, the official Mod Packager or
SGA Explorer)
Set up the options in the Texture Tool to use the colours/badges/banners of your choice (for existing DoW armies this may involve extracting the badge, banner and .teamcolour file)
Use the 'Compile TGA' option and select all of the Marine WTPs
Mass-convert the TGAs to DDS files (either with the experimental functionality in the tool or through another tool or art program) - must be DXT1 or DXT5
Rename all of the new DDS files to remove the "_default" section from the name
Use the 'Make RSH' button and mass-create a new set of RSH files for the Marines.
Hope that helps and makes sense