But in theory you could just use iFile and copy the audio book from itransmission folder and paste in any of the audiobooks app available in the appstore. Also, its important that the audiobook app supports the file type. You could see that in the description of the app.
I haven't tried this,
But you can try placing inside any tweak on cydia(with ifile of course) that allows music to be imported onto your iPod.app I.e mewseek
And try importing it as a song, it should play just fine.