Not sure if this answers your question, but if you turn the knob on the AFSCP to PLAN and zoom back to say, 20 mi, you can use the up/down arrows on the flight plan screen to cycle through the waypoints. Turn on the constraint button to see alt and speed constraints. In the real airplane, we use the “tire”, or little wheel on the KCCU (keyboard cursor control unit), next to the 'potato' (track ball), to roll through the flight plan.