mcukl won't work, as I want something running self-contained (i.e. something I could run on a network not connected to the Internet, but connected to other sites over a WAN?).
JWchat relies on Java, and doesn't integrate with EyeOS as well as I'd like. It requires extra set-up and as far as I can tell likes to pop out its own windows (no good). I've looked at this one before.
If you have your own jabber server muckl could work. I would look at it again. There is no difference between the wan or internet... the behaviour of the software is the same.
JWChat does not require java, double check that. It does want to popout eyeos, I am currently looking at modifying this behaviour so it stays inside eyeOS.