To 10.04 [all flavours] upgrade to 11.10

apt-add-repository http://archive.unbuntu.com/oneirc
apt-get update
apt-get upgrade

then boot the live-cd run the installer, do not try to change the system further after the apt-get upgrades, the upgrade will install the basic files required for 11.10 to be able to upgrade the installation so don't make any changes, just boot immediately after the upgrade has completed.