Aamir,
Just to be clear, the chat platform within xFlow and the one within USS are two completely different platforms.
Within xFlow you can use the Collaboration application to allow analyst to chat between themselves. Since "End Users" don't log into xFlow, they wouldn't be able to participate in these chat sessions, they are purely for analyst to analyst communication. It's also not possible (in up to 17.1, at least) to do any remote sharing.
The USS Live Chat feature is leveraging Support Automation, which has the possibility of chat and remote sharing.