I've finally managed to find a chatbox that I could make work on the site. I hope you like it. Its located at the top of the forums listing page.
To see the larger full version of the chat window click on the word "Chatbox" in the blue bar and from the dropdown menu choose "View Chatbox full".
For those that don't like the Chatbox, you can roll it up out of the way by clicking the little white up arrow on the right of the blue chatbox bar.
To edit or delete your message click on the box on the left of it..