Not sure why you'd want to do this as turning off GPS can also mess with things like speed, distance and heading. If you look at the track on a map, you'll also get straight lines between the points when GPS gets turned off and back on. When you turn it back on, it can also take a bit of time to re-establish a GPS lock.
In order to use my watch like my gps Oregon 450 I plan to leave at home. When I hike for a few days I just need to sometimes check my position in the watch and also check my altitude and vertical speed. I also need to have an automatic saving position when I turn on the gps.
Unfortunately the expédition mode is too limited : no altitude, no vertical speed and the minimum of automatic position is 15 min. I would like 3 or 5.