[Nisgeis]

The AO hack mentioned above will not give you full control, unless you want only a black and white image / severely restricted pallette. The stock skins are mirrored to save texture memory, so that both sides are the same. The only way to get the diffuse texture to not be mirrored is to re-map the UVs with a 3D package for a specific part. This will cause a lot of issues with compatability though, as you will need to replace the .dat file for each sub you un mirror.