Launchpad lists a version from this month for 12.04 (https://launchpad.net/~js-reynaud/+archive/ubuntu/kicad-package-daily-stable).
(http://i.imgur.com/aihkl6D.png)
ou should be able to install the .deb (https://launchpad.net/~js-reynaud/+archive/ubuntu/kicad-package-daily-stable/+build/8402995/+files/kicad_0.201512070431%2B4029%7E14%7Eubuntu12.04.1_amd64.deb) via SoftwareCenter. If that doesn't work try:
sudo add-apt-repository ppa:js-reynaud/kicad-package-daily-stable
sudo apt-get update
sudo apt-get install kicad
After you enable backports (https://help.ubuntu.com/community/UbuntuBackports) in general and add those listed on the site liked above under "Dependencies".