This builds a module called thinkpadacpi, which is a replacement for thinkpad_acpi.

The difference is it exposes all the laptop's LEDs in /sys/class/leds; not only the safe ones (the default config in Arch's kernel builds).

To disable thinkpad_acpi so this can take over:

sudo tee /etc/modprobe.d/blacklist-thinkpad-acpi.conf <<< 'blacklist thinkpad_acpi'