ちょいメモ

II. For Beta4 up to r198:
IMPORTANT: To install versions from Beta4 onwards, including r121 and the latest r198, make sure that you have U-Boot installed. For details, see U-BOOT/Emergency system installation and upgrade.

Download your ROM choice from the Downloads Section
Extract the 3 files - autoboot.sh, kernel.img and rootfs.img - to the root of your CF or SD/MMC card.
Make sure the Zaurus isn't plugged into AC power.
Remove battery for at least 5 seconds.
Replace battery (replace battery cover, lock cover), plug in AC power.
Press and hold the "OK" button on the keyboard.
Turn the power on, the Zaurus should boot into the Emergency system .
You'll be asked whether to proceed to install pdaXrom or the emergency system. Press "y" and then [ENTER].
Then you will be in a bash prompt (heading with a hash "#"). Switch to the location where the release files are:
cd /mnt/card (or cd /mnt/cf ).
Run the installation script by typing ./autoboot.sh
(the last dot "." is necessary)
Then you'll be asked once again whether to install pdaXrom or the emergency system. Again, press "y" and then [ENTER].
Flashing will then begin. Just let it do its job. It may take minute or two.
After flashing is done, the system will reboot automatically. Installation completes.

いまさらpdaXromかよって？・・・