Just figured away to do it.  Start with a new ac ready for to at Sea, select desired ac, turn on everything on the overhead panel including the IRS, reload flight plan and reprogram the route on the FMS.  Then on map mode, reset the flight to the Altitude, as, heading and lat and long, date and time from where you last left off.  Got to get the gear up fast but it seams to work and not take too awfully long.