Enabling brightness control is moderately easy (I’m pretty sure they worked out of the box on slackware).
Go to https://github.com/codingtony/acer-brightness-linux-acpi and follow the instructions. Change
/etc/acpi/events/acer-tm-brightness-up with the correct events:
event=video/brightnessdown BRTDN 00000087 00000000
event=video/brightnessup BRTUP 00000086 00000000
Restart acpid and the shortcuts should start working.