by car: drive via Sion up to Thyon. Thyon 2000 is the very last resort at the top of the mountain at 2093m above sea level. The drive up to Thyon from Sion takes ~40 minutes.
You can drive either via Montreux or through the Lötschbergtunnel. Depending on the traffic one route might be faster than the other. During holiday season I personally recommend driving via Montreux.

by train: Zurich - Bern - Visp - Sion - Thyon (5h)
Geneva - Sion - Thyon (4h)

airport via Zurich or Geneva. if you have your private jet, there is the option to land on the small local Sion airport...