running multiple distros (LSB-internal use)

Perhaps lsb-discuss isn't the best place
to put this question, but I can't think of
a better one.  This has nothing to do with
the LSB spec, but does affect LSB team
internal operations.

The LSB team is building up a battery
of machines for the different supported
architectures, so that we can test things,
do builds, etc.

However there's a desire to have multiple
distributions resident on some of the
machines to test cross-distro compatibility
when we do silly things like, say, muck
with the C++ abi.  Debian has a fairly reasonable
way to set this up, providing support
for installing into a chroot so that you
can run, say, "stable" on the base machine
and "testing" inside a chroot.

Does anyone have advice on good ways to
set this kind of thing up for rpm-distros
in general, or for any specific distros?

I've done something like this on a machine
here in my office which has nine different
ia32 distros on it, but I've done those
by cd-installs each to an empty partition;
we don't necessarily have access to physcially
plug media into the lsb build machines (or
even to reboot them, for that matter), so
a different "set up a chroot" mechanism
is needed.

You can drop me a line privately or post
here.

Thanks,

Mats