We have recently added VMWare ESXi as a supported operating system. We also support automated reloads of this operating system from within our control panel.
You will need to register on VMWare's website in order to retrieve a license key. Once you have received your license key you can follow this guide on entering it. This is done from within the vSphere client under the Home > Inventory Configuration Tab.
If you do not obtain a license key your VMWare ESXi evaluation period will expire and your installation may cease to function.