If talk (which isn't included with SME9) is what you're after, then SSH has nothing to do with what you're looking for. Is it your goal that users who are logged into the shell (whether via SSH, telnet, or locally at the console) on your SME server be able to chat? If so, then yes, talk should do the job, and 'yum install talk' should get it installed. If you're looking to do something different, please explain further so we can help you.