I was playing with this type of idea last night (wanted the Redguard cape over miner clothes. It...works. Sort of. Have an interesting issue I've got to sort out with the _1.nif version) . Basically all I did was copy the texture files for each outfit with a new name. Then I created a new alpha channel on the Redguard clothes texture so that ONLY the cape part would be visible. In NifSkope I then opened the redguard clothes mesh and chose my new texture to confirm I'd done the alpha correctly. Copied that branch to the miner clothes mesh (this took some fiddling with node string ids to make it work).
Basically, http://wiki.tesnexus.com/index.php/NifSkope_customise_an_outfit_for_beginners

Hi guys, can someone give a step by step on how you are doing this? Here Eisoj5 says to load the texture files first and then the mesh, whereas the tutorial says use meshes and then render textures using autodetect (doesn't work for skyrim, tried inputting skyrim folder, didn't do anything.)
How do I:
1. Make Skyrim textures display on meshes in nifscope?
2. Copy meshes/textures on to each other?
Lets say I want to put the studded skirt with the ancient nord chest, like you have. What are the steps?
Basically my current understanding is at:
1. Extract textures/meshes?
2. Open nifscope
3. ?????
Sorry for being a total noob. I would greatly appreciate any help.
Basically all I did was copy the texture files for each outfit with a new name. Then I created a new alpha channel on the Redguard clothes texture so that ONLY the cape part would be visible.
Specific question: What tool is used to do the above? I can't load textures into nifscope...