You can sequence the flight plan by deleting waypoints until the extended centerline is displayed but you might lose the FAF depending how many waypoints there are. That's the laziest way to do it.
Another way is to use the Direct to '' Radial In'' function. Just insert the FAF or the last relevant waypoint on the extended centerline and the radial in. Don't forget to pull heading, as ''NAV'' Blue will appear on the FMA.