Irssi has a fairly nice proxy feature. It's probably the best proxy I've ever used. Unfortunately, it has a few flaws and is very under documented.
I gave up on ever having a decent proxy and switched to the screen option but I still want to explain this feature so it's decently documented somewhere.
To setup the server you need to first install irssi and screen. Edit your configuration the same as you normally would to connect to any other server.
You want to proxy to load my default so edit ~/.irssi/startup and add the line "/LOAD PROXY".