My previous blog post talked about work being done on implementing an enhancement request which asked for the ability to remotely install an RHQ Agent. That feature has been finished and checked into the master branch and will be in the next release.
I created a quick 11-minute demo showing the UI (which is slightly differently than what the prototype looked like) and demonstrates the install, start, stop, and uninstall capabilities of this new feature.
I can already think of at least two more enhancements that can be added to this in the future. One would be to support SSH keys rather than passwords (so you don't have to require passwords to make the remote SSH connection) and the other would be to allow the user to upload a custom rhq-agent-env.sh file so that file can be used to override the default agent environment (in other words, it would be used instead of the default rhq-agent-env.sh that comes with the agent distribution).