More importantly, they are closed-source and we have no idea how the heck they do anything.
Our chances of helping you are slim,
no matter how much we might want to -- which once again shows how it is important for people to be open about their projects (especially when benefiting immensely from the work of others).
Have you tried asking on the Duokan support forums?
Alternatively, why do you NEED Duokan, rather than, say, KOReader which we support here?