Note: you can test this guide at staging.launchpad.net without affecting the production environment, but don't forget to replace "launchpad.net" with "staging.launchpad.net" in all links.
First off, you'll need a Launchpad account. You can create one at: https://login.launchpad.net/+new_account
Then create a personal package archive (PPA) to host the packages at: https://launchpad.net/people/+me/+activate-ppa The name will default to "ppa"; choose it wisely because it won't be easy to change it later.
In general you'd have to request an import of git code to Launchpad to create daily builds of it, but cjdns code is already imported to lp:cjdns-apt See https://help.launchpad.net/Code/Imports for information on code imports. This step can be skipped.
Finally, create a daily build recipe for the code at: https://code.launchpad.net/+branch/cjdns-apt/+new-recipe This will copy someoneweird's repository.
Recipe text should read as follows:
# bzr-builder format 0.3 deb-version {debupstream}~{date}+r{revno}-0
lp:cjdns-apt
the version string means: the version includes the number specified by the packaging, package build date and bzr revision of the import. The -0 at the end indicates that it has no Debian or Ubuntu-specific revisions. Also the ~ makes it lower than the real {debupstream} version. This version string is lower than a package built from source locally because local build would produce a release package and this is a daily build package.
Default settings should do, except two things: