I have meanwhile submitted packages for both modglue and cadabra to
the Ubuntu REVU site for approval. They are not yet through though,
and sit in a dormant state (it's incredibly hard to find sponsorship
for scientific software, I have to say). But if you are interested in
pushing the packaging for Debian, it is probably best to start from
those Ubuntu packages.
See http://revu.ubuntuwire.com for more details.
Let me know what you plan to do (I have more or less given up on ever
getting this into an official Debian repository).