it's a simple matter of adjusting your enroute speed so that you reach the STAR
I took part in those trials - in 1996 ! The type was B737-436 and the route was Aldergrove to Heathrow. The reason was the Boeing FMC had an "extra" page titled RTA - Required Time of Arrival. Departure clearance from BFS contained a time over BNN which was entered as RTA/BNN which would automatically adjust the cruise Mach number. We found the problem from the outset as cruise speeds below or above normal limits were being demanded and thus the percentage of arrivals within the 4 minute window was low - binned by ATC fairly quickly.