Ubuntu Guest Console (Configure Guest):

apt-get update && apt-get install linux-image-generic-pae
cp /etc/init/tty1.conf /etc/init/hvc0.conf
nano -w /etc/init/hvc0.conf (replace all tty1 with hvc0)
shutdown -P now
Citrix XenServer Console (Configure XenServer):

xe vm-list power-state=halted (write down UUID for TKL VM)
xe vm-param-set uuid=<UUID> HVM-boot-policy=
xe vm-param-set uuid=<UUID> PV-bootloader=pygrub
xe vm-disk-list uuid=<UUID> (find VB disk UUID)
xe vbd-param-set uuid=<VBD UUID> bootable=true
Start appliance and restart XenCenter Manager
Ubuntu Guest Console (Install XenTools)

mount /dev/xvdd /cdrom
dpkg -i /mnt/Linux/xe-guest-utilities*i386.deb (OR dpkg -i /mnt/Linux/xe-guest-utilities*amd64.deb for 64-bit appliances)
umount /mnt
sudo reboot