I highly suggest using silc.

irc is a really lame backwards insecure (in every sense of the word) protocol.
silc however is not. Silc builds on the command set irc people are familliar with.
It differs however in many ways.
First off each user can have any nick they want because user id verification is done via pki.
All of the service is encrypted with the ability for keys to rooms that the server has no knowledge of, eg: each client must have the key to decrypt. This means that the server can be used to relay things that even the server admin cannot decrypt.
It's free.
It's got a deb source

• deb http://silcnet.org/download/client/deb ./
• deb http://silcnet.org/download/server/deb ./

Assuming you have installed it you can just do this:

• /connect example.com
• /join #lostinthenoise
• /CMODE #lostinthenoise +k
• /KEY CHANNEL #lostinthenoise set MYSECRETKEYGOESHEREFORLEETNESS

Then you have a secret key on a channel that even the admin of the silc server does not know.The admin cannot findout without you leaking it to someone else.
It also has some other cool features that you can read about on silcnet.org

So go check it out.