[arch-general] Fn-F{5, 6} keys for backlight - how to disable native handling?

[Oon-Ee Ng]

I have an ASUS N56V where the Fn-F{5,6} keys do not work natively (no
output in xev when pressed). This is very easily worked-around using
acpi_os="!Windows 2012".

The resulting control is something along the 3-10 range (10 being
brightest and 0 being off, these are not the actual numerical values),
which means I can't dim my backlight beyond a certain value.
Similarly, using xbacklight and setting to 0 actually gives a "3"
backlight, not totally blank. Setting
/sys/class/backlight/intel_backlight/brightness to 0 does turn the
screen off though.

The problem is that if I write a simple script to adjust brightness
and bind that using xbindkeys, the native handler still works for a
fraction of a second before the value I calculate takes effect. This
results in a brief flicker everytime I press the keys.

Conclusion - I want to disable this native handling of Fn-F{5,6}, is
this possible or is this not software-controlled?