Microbox is a fork of Microwave (https://github.com/antimatter15/microwave) adapted to work with Wave in a Box server instead of Google Wave using the Data API and OAuth authentication. 
It plays on Google App Engine and its server side is written in Java.
It should be easy to configure it to work with your own Wave in a Box server.
Edit src/com/wavylabs/microbox/options/options.properties file
and replace waveDomain and port with your own wave in a box domain name and the port.
Also edit war/js/constants.js and replace the values accordingly.
Don't forget to edit appengine-web.xml and replace the app id with your own.
The source code does not include jars needed to build the project, but you can get them in the 'Downloads' section bundled in zip.
Have fun!

Example: http://micro-box.appspot.com