You're going to have to find your own IRC client, I used MacBitchX (freeware) for Macintosh. IRCle is another Mac client. For PC, mIRC seems pretty reliable.
To get to an Undernet server, sniff around at UNDERNET.ORG. I use "/server us.undernet.org"... which forwards you to the nearest/fastest server.
Me and Violet9 (Nyhne) have been lurking in the channel for a few days. It'd be cool to have some of you there as well. We could do some old school PANICking or coordinate Gridcosm blitzes or just shoot the shit.
I propose a 6pm (Pacific Time US) Tuesday meeting of the cyberminds on channel "#sito". Spread the word?