Ubuntu Wiki

To update your broken Karmic system from a live CD or booting from a jaunty/etc partition.

First mount your karmic partition on /media/karmic or replace /media/karmic below with where you have it already mounted.

sudo mount -o bind /proc /media/karmic/proc
sudo mount -o bind /dev /media/karmic/dev
sudo cp /etc/resolv.conf /media/karmic/etc/resolv.conf 
printf '#!/bin/sh\n\necho 101\n' | sudo tee -a /media/karmic/usr/sbin/policy-rc.d
sudo chmod +x /media/karmic/usr/sbin/policy-rc.d

sudo chroot /media/karmic apt-get update
sudo chroot /media/karmic apt-get upgrade
sudo chroot /media/karmic apt-get dist-upgrade

After you have booted karmic successfully, remove /usr/sbin/policy-rc.d

Note: This will only fix your system once the correct packages are available in the archive...