I am not a regular IRC user, but the link on project page for IRC does not connect. It took me some time to realize that I actually need to connect with "irc://irc.freenode.net:6667/hornetq" in order for it to work. Shoul that be updated it?
You need to download an IRC client, connect to the server and go to the hornetq room.
I believe some clients will register the protocol handler at your OS and they would handle the URL at your browser.
You will easily find more information about IRC on the web.