I have a similar issue and am also trying to get these to run on XenServer.
VirtualBox is not an option as it is a Type II Hypervisor while XenServer and VMware are Type I hypervisors. The virtual machines that are provided are in OVF format which essentially means that they should run on any Hypervisor that supports them. But, something is "hanging" during the boot process that XenServer doesn't like and ends up shutting the VM back down.
As far as changing my Hypervisor, that is a significant amount of work compared to what it would take to either correct the RCDev virtual machine image or build a machine using the installer packages that you provide on a Linux distribution of my choosing.
Since you commented on the pervasiveness of VMware and Hyper-V compared to XenServer, I'm curious as to why RCDevs opted for CentOS as compared to SUSE, RedHat, Ubuntu, or Debian - all of which are in the majority compared to CentOS.
Is there a documented process that RCDevs follows to create the VMware images? Maybe that could be leveraged to create images on other OS'es or even to create images specifically for XenServer by the community.