Maybe there comes a new Topo for Norway with Activerouting and then the Birkebeinertrack is on the map.
There are other solutions, like draw Your own track in Mapsource or Basecamp and put it on the Gps.

Or search for Birkebeiner gpstrack on the internet, for example I found one on gpsies :
Code:
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Download the track and use it on Your PC of GPS
Suc6