The most convenient airport nearby is Geneva. Other airports you could consider are Basel, Zurich, Lyon, or even Milan -- they would just involve longer journeys by train.
Travelling to Les Diablerets typically requires taking a train to Aigle, at the other end of the Lake of Geneva, and from there a narrow-gauge train (R24) up the mountain (15 km, about 54 minutes).
Our hotel "Les Sources" is only a short walk from the train station in Les Diablerets.
For information on Swiss trains, see the SBB webpage:
Tickets are often considerably cheaper when booked in advance, depending on how early you book.
The whole journey from Geneva is very scenic and well worth making by daylight.
When booking your travel, you should take into account that our hotel reservations span Sunday 21st evening to Friday 26th morning, but you can also drop your luggage at the hotel earlier on Sunday. Our scientific program starts at 9:00 am on Monday and finishes around 12:00 noon on Friday. All meals from Sunday dinner to Friday lunch are included in our package. The rooms have to be cleared by Friday 10:00 am, but it will be possible to leave your luggage in a bag room for the rest of the day.