Send a private message to BRenBot on IRC (you can say anything) and it will show you the commands:
<DeathServ> Valid Commands:
<DeathServ> register <gamename> <password>
<DeathServ> auth <gamename> <password>
Register your ingame nickname through this private message. Then when you join the game you have 60 seconds to identify. Do this by either using the "auth <gamename> " in the private message, or by typing "!auth <gamename>" in the IRC server channel (any mod/admin can do this in the IRC channel).