There's no registry setting AFAIK, but there is a way to "hack" the .exe (I think) using a binary editor and change some value from 15 to 1, but as I understand it such hacking is illegal.
A better option would be to use an add-on such as GPS Plus for MapPoint (
http://www.engo.com/mappointtoolbox/ ) or AGPS (
http://www.techgt.com/agps/ )
Eric