separate base from repository?

Hi,

I have a CD with a bunch of rpms, some of which I want to install with apt.
Unfortunately, apt-cdrom complains that there are no index files, which is
correct and presumably a common occurrence.
With some effort and softlink trickery I managed to use genbasedir to
generate the pkglist file, but obviously it was written to the hard drive,
not the CD. So, now what is next?

I don't see how I can tell apt-cdrom that the pkglist is somewhere else.
If I knew what apt-cdrom actually did, maybe I could do it by hand, but the
man page only says that "apt-cdrom must be used". Wouldn't it make sense
to add an option for that (or even better, have apt-cdrom do it
automatically)?

I could pretend the mounted CD is just part of the file system, and specify
it directly in sources.list, but actually my rpms are distributed over
multiple CDs, which is, as far as I can tell, exactly what apt-cdrom is
supposed to solve.

I cannot copy the CDs to the hard drive (not enough space, that's why I
want to install manually in the first place).

I guess I could find a different computer and burn new CDs with the
pkglists on it, but that seems exceedingly clunky.

Any suggestions?

Thanks,
Marcel van der Goot

P.S. If anyone were to add an option to have the pkglist outside a CD while
the CD contains the rpms, then allow for some flexibility in the naming:
the RPMS directory may not be at the top-level of the CD, and may not
follow the apt naming conventions (e.g., in my case its just "RPMS", not
"RPMS.something").

P.S.
I'm using http://fedoraproject.org/extras/4/i386/apt-0.5.15cnc7-6.fc4.i386.rpm
It has man pages for apt-get, apt-cdrom, etc., but not for genbasedir,
and in fact none of the man pages even mention the existence of genbasedir;
that's inconvenient.