$ apt-get install polipo 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: polipo, tor, torify, screen and irssi. Default settings work fine for now.

  $ /etc/init.d/polipo start
  $ /etc/init.d/tor start

  $ usewithtor irssi

connect to the server, change your nickname and join the channel:

  $ /connect irc.oftc.net -p 6697
  $ /nick your_new_nickname
  $ /join #cryptoparty

For further information see the Torprojects Torify HowTo (irssi).