The primary usecase for SupportFacet is to gather some diagnostics info that should be sent over to "someone" that would make use of it - logs, thread-dumps, temp dirs, whatever applies to your managed resource. As you correctly said, it is an experimental feature. Unfortunately there is no GUI for it, you can only access it programatically through the "SupportManager" in the CLI. The SupportManager has a single method - "getSnapshotReport" that, upon invocation, will contact the agent, call the SupportFacet method on the appropriate resource component, and put the resulting file in the downloads section of the RHQ server, for which it will return the URL for you.
On the other hand if you are looking for merely showing log entries from some log files, you may want to try the Event subsystem. I could find very little docs on it, unfortunately, but you can take a look at for example at the JBoss AS 4 plugin ($RHQ_SOURCE/modules/plugins/jboss-as) that uses them.
Using the Event subsystem basically involves defining some "event" tags in your plugin descriptor and then configuring the EventContext (ResourceContext.getEventContext() ) during the start method of your resource component.
Please be aware though that the event subsystem can generate a substantial load on the database and so you should use it with care.
Thank you for your fast replay. Yes the events looks much more better for my purpose, I will explore them. I developed only the very simple HornetQ plugin few months ago so I am not familiar with all RHQ features.