Valmorel

That's right. Only by bus from either Aeroport or Gare Routier. There used to be a train from Gare des Eaux-Vives to Saint-Gervais but the station was closed in 2007 for renovation and won't be re-opened until 2017. There must be a way to get to French ski resorts on train, but it will probably involve many change overs and take forever.