On line maps can be a bit tricky. For example the map in the link above is out if date and at least two of the lifts on there aren’t running. Its also for Led Gets, buts that’s another matter 😀
Basically up the super morzine, then the chair. Ride the ridge to just below Avoriaz and drop down to Linderettes. Up the chaux fleurie chair and over into the next valley. There’s a track that goes from the top of the bottom chair, slightly up to start, to Chatel. To get back you can ride straight back from the top via Linderettes. Start on the road then use the tracks back to the river valley.