Comparing with flashlight on and off.
Off
/sys/class/led/led:switch_0/brightness = 0
/sys/class/led/led:torch_0/brightness = 0
/sys/class/led/led:torch_3/brightness = 0
On
/sys/class/led/led:switch_0/brightness = 1
/sys/class/led/led:torch_0/brightness = 127
/sys/class/led/led:torch_3/brightness = 127
I'll need to test if changing these will trigger the light, certainly just making switch_0 = 1 doesn't work.
Not sure if this is the correct way to interface with these.
As for monitoring for new messages I'm wondering if dbus-monitor could be used...