This is a Lightstream Labs feature. For info on enabling Labs features please visit
To obtain the information for your scheduled event, you'll want to visit the page you wish to broadcast to, click "Live Video" in the share box, and then switch to the "Connect" tab. There you'll see the Ingest Server (Server URL) as well as the Stream Key.
You'll then want to import this information into an RTMP Destination as shown in the gif below: