The game uses formats similar to the Street Fighter IV ones, with some changes!
The game files are packed in cpk files, and 3d models and textures are in .emd and .emb files.
You can download all the tools you need from this link: LibXenoverse (by DarioSamo).
You'll find a tool to unpack the cpk archives and some little programs (in the bin folder) to do some useful things with the files you'll obtain from the unpacking process!
Things are pretty self explanatory, if you don't know how to use one of the programs, open the command prompt (or cmd) and drag and drop the .exe, press enter and the needed instructions will appear!
The most intresting things you need to know is that the .emd files are 3d models and .emb files are the textures.
After the extraction of the textures, you need to recolor them using Gimp, Photoshop or what you like most, that's because of the game itself, basically it's a trick to save space and to do the user colored stuff!