$ apt-get install tor torsocks irssi
In order to make sure you are running the most up-to-date version of tor please refer to torproject.org/docs/debian
Now you should have installed: tor, torify, screen and irssi. Default settings work fine for now.
$ usewithtor irssi
connect to the server, change your nickname and join the channel:
$ /connect -ssl irc.oftc.net -p 6697 $ /nick your_new_nickname $ /join #cryptoparty
For further information see the Torprojects Torify HowTo (irssi) or How do I configure irssi.