Good post. http://technomancy.us/162
We’ve found SSH, tmux, and Emacs to be a great combination for this. The host prepares his machine with a new user created just for the purpose of swarming, and everyone is given the username, hostname, and password to log in over SSH.
$ ssh firstname.lastname@example.org
$ tmux attach
Once logged in, running tmux attach allows a user to join an in-process session started by the host, and control can be passed around as discussion progresses. If someone has an idea for how to address a certain problem, they can just try it out straight away.