It is, in theory, possible to configure any network service to be reachable over the Tor darknet. This includes instant messaging servers, like the XMPP server EjabberD. Conversely, it must be possible to configure your instant messaging client to connect over the Tor network. I used Pidgin as my client, and here's how I did it:

I set up a copy of the web proxy Polipo and configured it to work with Tor.

I then created a new XMPP account in my Pidgin client which connects to the XMPP domain the server was configured for (let's say it's 'xmpp-domain', though …