I have just the perfect thing for you:
The worlds second largets XC ski race, April 22nd at Finse/Geilo!
Arrangers set up trains from both Oslo and Bergen.
Many years 14000 participants, 38km freestyle, plenty of snow, many
from Norways national XC and biathlon team race it.

http://www.turrennklubben.no/tur_skarverennet_2005.html
http://geiloil.no/comweb.asp?segment=3&ID=23

Accomodation he
http://www.geilo.no/render_vinter_en...ent=7&session=
Train he
http://www.nsb.no/