Set the acpi_osi kernel parameter in /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="quiet acpi_osi= "
Run
$ sudo grub-mkconfig -o /boot/grub/grub.cfg
Install asus-kbd-backlight
Add to /etc/sudoers for hotkey usage
{user} ALL= NOPASSWD: /usr/bin/asus-kbd-backlight
I haven't found a way to add acpi_backlight as a working kernel parameter for my system.
Install ponymix
Bind XF86AudioMute, XF86AudioLowerVolume & XF86AudioRaiseVolume