It's like IRC over SSH (or telnet).
Have every member of the conversation SSH to the same computer and run TTYchat. To enter a message, type '>', the message, and then hit enter. To exit TTYchat, type 'x' and hit enter. The conversation is held in 'buffer.txt', which in this version has to be manually cleared when it takes up too much space.
To install TTYchat, put the following in the terminal of the server:
The only thing needed to connect to a conversation is an SSH connection to the computer running the program.