@Sconio look on the xda forum, just Google : xda multirom pro 5 :

I have found help here : https://forum.xda-developers.com/google-nexus-5/general/port-ubuntu-touch-nexus-5-t2594874/page59
It's not difficult. It works with Android and Cyanogenmod.
If you do it, take some note and please write it on the wiki or on the forum asking for help to edit the wiki. That would help others.

Hello. I tried installing Ubuntu Touch with MultiROM and TWRP recovery without kexec-hardboot support enable, with the no kexec-workaround enable in the Recovery options, which resulted in a hard brick. I just want to warm people not to do this. CM12.1, CM13.1 and CM14 do not have the corresponding adapted kernel with kexec support, so don't use them as main ROM if you plan to install Ubuntu Touch, because the workaround available in the recovery will just cause a hard brick.

Beside that, following the steps in this video with the exact same version of software should get Ubuntu installed with MultiROM without any headache 🙂
https://www.youtube.com/watch?v=Cg0INhBx4tY

Hi,
this is my instruction to install it via MultiROM:

http://forum.xda-developers.com/showpost.php?p=65462235&postcount=3222

Installed developer build 218 its stuck at 1+ logo, and 219 build is throwing some error which states that multirom has been stopped to avoid file corruption.. On the move now will post details later if anyone wants them.

News 6/03:
MultiROM v33 is under development, just need patched kernel to boot heterogeneous ROMs (ex. CyanogenMOD and Ubuntu).

Thanks.

Thanks for reporting!

I forgot to edit the md5 hash when updating the manifest. sorry about that.

-Marius