The
old site is down, but you can check here:
http://darcs.complete.org/ for a source repository (not with isos, but it may get you started).
Here are the two pages I read when I used DFS. It was a fun experiment, but probably not worth the extra effort, unless you have very particular needs.
http://linux.suramya.com/tutorials/Install_DFS/
http://www.linux.com/articles/41627
Edit: If you already have a working Debian installation already, I think that you can install the
dfsbuild tool there. That would allow you to create custom isos yourself.