Downloaded the CM GPL Script for Xen from https://www.virtualmin.com/documentation/cloudmin/gpl
Running it I found a couple issues. The script installs xen and xen-libs from the repo chosen but those packages don't exist for CentOS 7 so I changed the script to read xen46 and xen46-libs. The script runs fine up until you hit the firewall section and then the grub loader.
Opening port 10000 on IPtables firewall .. IPtables is not available .. failed ... Configuring GRUB to boot Xen-capable kernel .. GRUB v1 not found on this system! Cloudmin GPL has been successfully installed. However, you will need to reboot to activate the new Xen-capable kernel before any Xen instances can be created. ---
I fixed the grub loader to use the new Xen kernel and then rebooted. Server come up fine. When I try to use the xl command, I get errors.
[root@localhost ~]# xl info xc: error: Could not obtain handle on privileged command interface (2 = No such file or directory): Internal error libxl: error: libxl.c:116:libxl_ctx_alloc: cannot open libxc handle: No such file or directory cannot init xl context