Debian Live is the tool used to generate LiveCD images now for Ubuntu. There is a manual available for it that notes there is an extension that handles producing Ubuntu-style LiveCDs but says very little about what said extensions do. Ubuntu is listed on the downstream projects page yet there is nothing for our usage of Debian Live.
There is a blueprint from the O cycle logged on the wiki logged by Colin Watson. That's the only thing I could find that tangentially talks about this on the wiki. Elsewhere searches just lead back to the web-based copies of manual pages.
The main reason for doing this is to avoid going down the route discussed here of building a bespoke netboot image with a tightly tuned preseed for my BeagleBoard-xM. A way to do this using live-build would be nice. It would also be nice to be able to keep disc images re-spun with updates for those Erie Looking Productions may pick up as collaborators who want to migrate to *buntu.