Sorry, I am posting an answer for myself in the past (time travel) or any poor shlub stuck like I was. (this should appear in a Google search)

The fix: for Asus to make the fn + f9 keyboard combo work! You need to install the keyboard filter software, then the hotkey software but here's the kicker you need to install the correct touchpad driver (the windows one won't do it.) The synaptic package will install on any machine even if you don't have a Synaptics device! In my case installing the Elantech drivers made the hotkeys app see the touch pad and turn it off!

phew!

Good luck.