Confirmed working on my N4 using the following instructions:

1. Download quantal-preinstalled-armel+mako.zip and quantal-preinstalled-phablet-armhf.zip from: http://cdimage.ubuntu.com/ubuntu-tou...ntal/mwc-demo/
2. Push files to sdcard
3. Reboot into recovery (using CWM here..)
4. Flash quantal-preinstalled-armel+mako.zip
5. Flash quantal-preinstalled-phablet-armhf.zip
6. Reboot and enjoy

P.S.: This method retains CWM recovery. I haven't tried flashing the imgs via fastboot yet though..
Nexus 4