Our IRC meetups happen on the #drupal-geo channel of irc.freenode.net. There are instructions and helpful guidelines on the Drupal IRC page.
You may want to install an IRC client on your computer, which makes things a little easier. The Drupal Dojo has some handy instructions to get you started.
You can also login on this page and get started chatting right away. Choose a unique username, and you can safely omit the password.
