You can use the Config to set up an Event type, (defaults are Gas, Damper, None, None), but you can change the name or use one of the None's. Then you can set up Buttons (see the buttons Tab in the Config window), that makes use of the Event type etc.
Then while roasting hit the appropriate button you have configured to signify the event. So in your case maybe you set the Event to Prog then a set of Buttons that don't actually take an action but will add the event to the chart. So giving the Buttons values of say 1 & 2 & 3, you should show a P1, P2, P3 on the chart when you press the button.