Lucky you - going to CC. Well, I'm a norwegian myself and have visited CC a couple of times - I just love that island and their "go slow" way of livning there. I really miss the place.. Anyhow - I think that Continental airlines are the "best buy" to Belize City. Try internet www.gotogate.no
or call World adventure travel in Oslo - they know their business, and are really service minded.. Alternatively you might try Oslo-Cancun, and then take the bus to Belize City.