Well, your master 120Amp breaker is required between the battery and everything else (as per the diagram). This will, in all cases, disable everything.
As far as a disable switch on your operator console, check out this diagram:
http://ifirobotics.com/docs/competit...guide-reva.pdf
DO NOT REVERSE THE PIN #S!!!!!! make sure that pin 1 is pin 1 on your connector. THATS RIGHT!!! P1 is not PIN 1... the trace with the number 1 is pin 1. I have reversed this, and it costs $150+shipping to fix.
And of course, you can always do a programmed e-stop, which only works as long as your program works
(that is what you are trying to test... right?)
Jacob