Hmmmm I'm not sure what your asking here, a black textured object should be the same as a multi-colored one just so long as they both Have a texture. If the object does Not have a texture, then you need to either add a material layer in a 3D program like Blender, 3DSmax or Maya, or use Nifskope to paste a texture branch and material from another model that does, and customize the texture it loads from there. I'm not sure of any specific tutorials that teaches this in Nifskope, but the Blender/Gimp tutorial Artisten and I did does cover changing the texture of a model in Nifskope and general Nifskope navigation if you need. Materials are also covered in the Blender side of the tutorial.
Luck,
Miax