Profusion has an unofficial [IRC channel] on [starchat.net]. It can be accessed through an IRC client at irc://irc.starchat.net/proelium or [through your browser] (uses a Java applet). Note that Starchat has its own [acceptable use policy], which is different to [Profusion's].
When using the Java chat, you may get a pop-up asking if it's okay for the Java to run. It is, so click "OK". You should then see a form asking for several bits of info, like nickname, password, channel, and server. Put your Pro username into the nickname box (so we know who you are) and click the "connect" button. Presto, you're on IRC!