found the answer: http://fabiobaltieri...-led-subsystem/
switch off:
echo 0 > /sys/devices/platform/leds-gpio/leds/alfa:blue:wlan/brightness
switch on:
echo 1 > /sys/devices/platform/leds-gpio/leds/alfa:blue:wlan/brightness
List all possible LED Names:
ls /sys/devices/platform/leds-gpio/leds/
This is the answer for Mk IV, I don't know if it is true for MK III