I’ve posted an Instructable showing how to build and install an electronic derailleur. If you like this project please vote on the Instructables page. This has nothing to do with my bike computer and is meant for people who enjoy building stuff themselves. A more complete and finished product including my bike computer is in the works.
For now the Arduino sketch, schematics, Fritzing diagram, bill of materials and CAD diagrams can be found on the github.