Licensed under the GPLv3+.
See FBInk ;).
See the basic example, it's basically Python + cffi + FBInk ;). There's absolutely zero higher-level wrapping, so you can pretty much follow FBInk's C API.
Because cross-compiling Python & Python modules is fairly hellish, this is bundled with my usual Python packages (Kindle & Kobo) ;).
For another very minimal example, see how this is used in LibrarianSync ;).