You're in luck; after spending many hours trying numerous methods to modify textures, I've finally found a vector that works! :D Proof of concept is attached (a kitbash using nipples from some STO textures).
I'm not the best texture artist out there, so I'll post the base nude skin textures and normal maps here for others to take a look at and try their hand at modifying if they want. While people are working on that, I'll work on writing up exactly what I did to get new textures to load.
Note that for the diffuse textures (that end with _D), you'll likely want to follow the instructions in this post unless you're already well-versed in texture editing:
http://www.gamevixenzone.net/saucy-requests-24/textures-needed-sto-484/#post6291
Also note that the normal/bump maps (those that end with _Nx) are of a greenish variety, of the same type as the ones shown in this tutorial video:
NBA 2K PC Tutorials - Creating Normal Map "Green" Textures - YouTube
Finally, you'll want save all your edited .dds textures with DXT5 compression, and generate mipmaps.