You don't, the OP lists a webchat interface to the irc channel.
The quakelive irc channel is subject to the same terms as the rest of the site, there is a bot there that helps to enforce them.
Quake Live is reliant on third party programs to do something as simple as gather players for a game. IRC is not an ideal form of communication when you are dealing with a game in 2011, going on 2012. A chat reformation is needed to broaden the community. The very fact this thread has been stickied through all the rest testifies that people are social beings and would like to get together in an easier manner.