From multi-boot to multi-guest?

Xen is mostly of interest to me so I can do development and testing
on multiple operating systems without rebooting. I already have
several /boot and root partitions for several OS setup on my machine.
I can also boot the Fedora Core 6 xen kernel as dom0, but my experiments
with the redhat virt-manager tool seem to indicate the only way it can
create new guests is if I want to install more copies of fedora.

What I'd really like to do is just turn the various /boot and root
partitions I currently have into guests under Xen. Are there any
instructions a person starting with absolutely no knowledge of Xen
can follow to do this?

Things I can guess:

I'll have to change my fstab file in each OS to not mount other
partitions owned by other OSes.

I'll have to give them all unique host names and IP addresses.

Things I have no idea how to imagine:

How do I setup the network for each guest?

Is creating the guest just a matter of building a proper config file
to point to my existing boot and root partitions and pass to xm?
If so, what the devil goes in the config file (which
file names are specified relative to the filesystems mounted on
dom0 and which ones are relative to the domU mountpoints)? Or
do I need to copy some info out of the existing partitions so
it lives somewhere on dom0?

How do I make sure the kernels in the existing boot partitions will
support paravirtualization? (I have no fancy new Pacifica or
Vanderpool instructions on my machine).

What have I missed that will drop me into virtualization hell
when I try this stuff? :-).

Thanks for any pointers to get me started! (Speaking of getting
started - are there any web pages on Xen that are somewhere
in between the Sunday Supplement and the Phd level - everything
I find seems to have hype with no content or content that only
makes sense if I was in at the beginning of the long conversation
I missed :-).