This question already has an answer here:
I have RaspberryPI with no GUI==(no x.org) I like to bind the useless window/super key to be my prefix. Using Arch for ARM runs great.
If think this is going to take more then simple mod in the tmux.conf file.
After some Googling found post with a command: dumpkeys | grep -E "keycode *125|126" That command give me a blank line.