Use this wiki plugin to chat using Jabber. The plugin runs a Java applet that connects to a local (same machine as the webserver running Tiki) Jabber service, which is a open protocol for chat, using the Extensible Messaging and Presence Protocol (XMPP), which is an open, XML-based protocol for near-real-time, extensible instant messaging (IM) and presence information (a.k.a. buddy lists).
Requirements
A Jabber server on your web host (same PC)
JAVA enabled browsers
You can only use this plugin to connect to a jabber server that is running on the same server as the http server for tiki. This is a constraint of the applet for security reasons.