This is work-in-progress. Source of this information is http://www.users.on.net/~hluc/myZaurus
Most information about the SL-C3000 found on the net is in Japanese and a lot of the instructions out there are for earlier models of the Zaurus. Although a lot of that info is still valid because the C3000 is backward compatible with lots of the older models not everything works. Since the C3000 is newer, it has extra capabilities those guides do not mention. Also sometimes things that worked in the older version do not work on the C3000 anymore due to it being implemented differently on the C3000. This guide is intended specifically for the SL-C3000 model (also sometimes referred to as Spitz) but a lot of the stuff can also be applied to similar models.
Some of the customisations require some additional files which should be downloaded first. Create a folder called custom on a CF/SD card or via the USB connection to /home/zaurus/Documents and copy the files found at http://www.users.on.net/~hluc/myZaurus/custom into that folder. Most the instructions below assume that the files have been transferred to /home/zaurus/Documents/custom
The first thing you probably need to do is to install a terminal/console application and backup your Zaurus.