Rated 3 out of 5 stars

"Right, but it has a trigger so you can launch your own script that actually plays whatever you want."
I have no idea how to do that.

This review is for a previous version of the add-on (0.4.8.1-signed).  This user has a previous review of this add-on.

#!/bin/bash
# play.sh (need to chmod +x)
aplay /usr/share/sounds/purple/login.wav

Put this script's path into the 'Launch on count change' preference.
For further support, please join https://github.com/foudfou/FireTray/issues