Help with "merge" dds files

Hi Experts!

Is there a solution to "merge" the assetto corsa dds files with the map dds files?
I've found a beautiful apxgp livery, but can't make the carbon fractal pattern work...

If you need, I'd send the files through PM.

I've found the topic about the problem above, but still can't find it work.
Any help please?

[www.grandprixgames.org]