Сначала надо добираться до Гренобля. Как добираться - написано ниже. Затем либо такси (около 50 км), либо доехать до Bourg d'Oisans (поезд, автобус), оттуда в Les 2 Alpes на автобусе (в день штук 8 рейсов, последний где-то ближе к 8 вечера).

Train from Geneva to Grenoble
Schedule: 3-4 trains a day, consult the SNCF's website
Duration: 2 hours
Where to buy my ticket: You can buy a ticket at the airport railway station for your complete journey to Grenoble or on the SNCF's website

Bus
Schedule: 3 times a day every day: 11h00, 14h30 and 19h30
Duration: 2 and 1/2 hours
Prices: 43 euros one way or 69 euros for a return ticket
Departure: Geneva Airport, from arrivals
Arrival: Grenoble Bus Station (Gare Routière)
Where to buy my ticket: from the Tourist Information-counter in arrivals