Don Orr
More info may be needed.

Is he looking for a way to mount a 4 jaw scroll chuck to the tailstock so it revolves?

Is he looking to mount a 4 jaw scroll chuck to the tailstock that does not revolve-just for alignment purposes?

Is he looking for a way to mount an actual cup to the revolving tailcenter to hold a workpiece?

Each question has very different answers. Let us know if you can get more details.