To clarify I want to install Ubuntu 14.10 using this method:
Download the system image flash-able zip (trusty-preinstalled-touch-armhf.zip) & device specific flash-able zip (trusty-preinstalled-touch-armel+mako.zip) from here.
Connect your device to the PC and transfer the trusty-preinstalled-touch-armhf.zip & trusty-preinstalled-touch-armel+mako.zip to the device’s storage.
Open a new cmd window and type in the following command to boot your device in recovery mode:
adb reboot recovery
Tap on Advanced > MultiROM > Add ROM
Set Choose ROM type to Ubuntu Touch
Set Share kernel with Internal ROM to Don’t share
Now tap on Next > ZIP file. Select trusty-preinstalled-touch-armhf.zip and start the flashing process.
Once done, again tap on Advanced > MultiROM > List ROMs
Tap on trusty-preinstalled-touch > trusty-preinstalled-touch-armel+mako.zip and start the flashing process.
Once the process is complete, tap on Reboot System