I have set up my own local repository for "os" for this very reason. No sense in going out to the net for stuff I already have. Here's a link on how to set up your own Server:
http://freshrpms.net/apt/server/
So then I put a line in my sources.list that point to my server for "os" and another one that points to ayo.freshrpms.net for "updates" and "freshrpms".
I don't believe there is a way with the apt for RPM to use the CDs directly even though in the
sources.list man page has a "cdrom" URI. Then again, the
apt-cdrom command does exist which would indicate that maybe it's very simple. Let's check this out some more, maybe it's very easy.