anybody know?
Not for sure, but here is what I see. In my 818nd manual, there is a pin-out diagram for the microphone jack. There is a pin for FAST, UP, DOWN, and a pin for GND. I suspect touching FAST to GND will toggle on/off the running man. Note: there is a separate MIC GND which is only for MIC speaker ground I would bet.
I found a schematic for the MH-31 microphone and it appears consistent -- Looks to me like the FAST, UP and DOWN all use the same GND separate from MIC GND. and these switches all appear to be normally open push button type.
Disclaimer, at the time of this writing, I have not attempted. I will try it and let you know how it goes.
Regards,
Jeff KG5AHC