Update to MultiROM v21a (http://devhost.xda-developers.com/IIO) or newer and recovery 2014-01-26 or newer Go to recovery, Add ROM -> select Ubuntu Touch -> Next Two files - one is device specific, second is the Ubuntu Touch system: Device-specific file: ubuntu-touch-4.4.2-system-armel+hammerhead.zip (mirror)

System file (this one is from ogra with MIR fixes): ubuntu-touch-4.4.2-mir.rootfs-armhf.zip Continue installation and profit. Needs about 2GiB of free space, by the way.

First testing builds of Ubuntu Touch for hammerhead were released, read https://lists.launchpad.net/ubuntu-phone/msg06116.html They are compatible with MultiROM and can be flashed via TWRP when packed to ZIP FilesIt can't be installed via the MultiROM Manager app because it is not official build, therefore it is not using system-image OTA system on which the app relies.