From Geneva:
The train station is located in the heart of the airport, two direct trains every hours to Montreux. 1 hour by car and 1h08 by train.
From Zürich:
A train station is located in the heart of the airport. Take the train direction Lausanne, then from there direction Montreux/Brig/Simplon. 2h20 by car, 2h51 by train.
From Basel or Bern:
These two cities have an international airport and are very well connected to the train network.
For Basel about 3h00 and Bern 1h00.