Playing around with 6.0.1 and loving how well it runs via USB on my Eee 701.

While looking at the Knoppix 6.0 notes, I see this following item in the Microknoppix section:
6. A persistent image for saving personal settings and additionally installed programs, KNOPPIX/knoppix-data.img, is supported on the boot device. That way, even the boot system and startup scripts can be changed in the persistent image.
How would I learn more about that -- and how do I use it? Are there some docs that folk could direct me towards?