First you will need to mount the guest-tools.iso which should come pre-installed on the XCP-NG client.
Next you will need to reboot the system in order for the ISO to mount.
Once the system is rebooted you will need to mount the ISO to the /mnt directory
sudo mount /dev/cdrom /mnt
Now for the install. Type "y" when asked to install.
sudo bash /mnt/Linux/install.sh
Now we can unmount the ISO and reboot.
sudo umount /dev/cdrom
sudo reboot now