Tested with OpenNebula 5.2.1.
You need sufficiently new tools for this -- e.g. Debian stable (as of June 2017) has a version of cfdisk that causes trouble. Packages from up-to-date Ubuntu 16.04 should work.
First install the required packages:
sudo apt-get install make qemu-utils libguestfs-tools
The Makefile uses sudo where root is required, so it must be configured for your user.
Also note that:
- any automount must be disabled, otherwise it could interfere
- don't run VirtualBox at the same time -- the kvm device is apparently exclusive access