Hi rgcda,
You can do it, but as Mark mentioned, that is a change to the firewall. You will need to open port 2144 to let the agent connect to the server and send its monitoring data, as well as resources and configuration.
I don't know why there are claims which this is not supported, or in the roadmap, but I can tell you that we have such solution and it works well enough, not for Hyperic but for vROps itself and we use it in QA environments. If you are OK with opening the port on the appliance, you will be able to monitor the machine's state and know whether the machine is up or down.