Sure, write a DCE device, that can launch OnLive appropriately, and pass back the window name to Orbiter, so that the window can be swallowed and controlled appropriately. Then you would either expose the appropriate commands to it starting with the device template, and then figure out whether you can either communicate with the running onlive instance via sending it synthetic mouse clicks, or via some other form of communication (named pipe, socket, etc.)
You may want to read the Developing a DCE device in the wiki to start.
-Thom