How to add export formats to Preview.app?
The simple answer here is No. 

You cannot add formats because the libraries and support for those libraries must be compiled into the Preview application.  Since Preview is not an Open Source project, there is no access to the source code to add this support and subsequently compile it.

I investigated creating a plugin, however that also hit a dead end as there is no way to access the Plugin API (if it exists)  

https://discussions.apple.com/message/16054059#16054059

The best way to address this is to let Apple know about it by submitting feedback:  http://www.apple.com/feedback/macosx.html