Feather Linux (a Knoppix remaster) has an interesting new feature, I wonder whether this would make sense to integrate into Knoppix:

Added customisation ability - simply place all the .deb, .tgz and .tar.gz
files in an /extra directory on your CD-ROM or USB stick, create a
"deblist" file which contains the names of the .debs and the order to
install them, and then boot with "knoppix custom".
http://featherlinux.berlios.de/changelogs