Actually, it might be possible to change it by following these instructions:
https://wiki.archlinux.org/index.php/reset_root_passwordOn the Zaurus, you can append the
init=/bin/bash
part in the boot/boot.cfg file, at the end of the APPEND label. I have tried it on my SL-C1000, by plugging the SD card where Alarmz is installed on my laptop and modifying the file there. I have put the SD back in my Zaurus and it has directly booted bash, skipping the rest of the boot procedure. Unfortunately I have not managed to remount the partition as read/write, since a wrong keymap was loaded and I wasn't able to type the / character.
In your case I believe that Arch Linux is installed on your internal Microdrive, so you'll need to first install Alarmz on an SD card, boot it via kexecboot, mount the root filesystem on the Microdrive (it should be /dev/sda1), modify the boot/boot.cfg file there as explained above and reboot, this time booting the system from the Microdrive.
Varti