If you are using Citrix Xen, open-source Xen and KVM virtualization, we now have Debian Jessie images available for download. Just login to Cloudmin and go to Cloudmin Settings -> New System Images, search for Jessie and download the one that matches your preferred virtualization type.
Both images include only the base distribution, so you will need to install Webmin or Virtualmin after creating a virtual system from them. Images for KVM are available in both 32-bit and 64-bit distributions, depending on the architecture of your host system.