I can not get my Z550 to easily display coordinates of saved favorites but....could be operator error.
Besides the import Mapsource routine, I found a work around on ZumoForums ...maybe this would work on the 660 as well
"On the Zumo, it's a little circuitous. You will need to turn the GPS receiver function off (Wrench > System > GPS Mode OFF), then browse the map to a Favorite, hit Set Loc to set the current map position as your location, then go back to the map screen, and touch the vehicle icon for the coordinates.
You can't get the coordinates of the pointer while browsing the map in live mode."