Some where in the thread there is a very brief how to. I can't remember where it is.

1)To start, download the firmware i posted here. I know it works with the Rumba. It is in post 90 of that thread. #90 I think there have been some changes to the main firmware but I haven't tried it out yet.

2) You will need to modify the Config.h file, the Pins.h file and the Marlin.main file. The firmware linked above should have the changed needed for the Rumba.

3) Make sure you adjust the offsets per the zenmaster videos on youtube.