I know it is possible, but it takes a long compile if the user wants to do it, could it be just made a feature in OSMC?
Here is a link with the patch for OpenELEC, which should work for OSMC, seeing as they both use the same kernel driver for the network interface.
You can do this via edit to config.txt or a startup shell script
https://www.jeffgeerling.com/blogs/jeff-geerling/controlling-pwr-act-leds-raspberry-pi
He is talking about adding that function for the Network LED’s 
Silly me.
Here is another way to do it
https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=72070
(Would need build tools on RPi to build own from the source)
Still requires some compiling, that is why I am asking for it to be a feature.