Directions:

tar zxvf xen-4.5.0.tar.gz
cd xen-4.5.0
patch -Np1 -i /path/to/xen-4.5.0-slic.patch
sudo /path/to/grab_slic.sh .

Requires /sys/firmware/acpi/tables/SLIC to be available (may not be visible in EFI boot.)