Majik.
Yep..I rode from Morzine to Lake Montriond last year but this was following the road and a bit of an uphill slog but not too bad, the Chatel runs (posted by Karve above) are a bit further.
Although I havnt confirmed it (ill check with Paul at my bruvs chalet) but I think the best route is go into Morzine, get cable car up Super Morzine (this is mountain other side of town opposite the main Pleney one), go up there and then its flat/downhill till the Les Linderts DH runs, the Chatel runs are just below that.
Campery is quite a bit further but looking at my maps there are plenty of cable cars which take you up and over the Swiss border and into Champery.
Some of the guys I went with last year did that route and I recall there is a youtube vid of guy doing the whole trip, this was on the Chamepry WC day where of course it pissed with rain and Danny hart did his amazing run
Andy