From the parking where the road ends, take the ski de fond track up the road D205 for about 4km, turn off south just before the Bergeriedes Tioures then drop down to the river and cross a small (THIN) bridge.
From there climb the slope and follow the torrent de Clausisto where the high valley opens out then bear to the east of the pic de Corniviet. The slope steepens until you reach a diagonal ramp trending eastwards leading to the summit of the pointe des Sagnes Longues. You can head up to the ridge and follow that or continue up the ramp and join the ridge right at the end.
Ski back along the ridge and drop off on to the ramp, (make sure you don’t do this too early). Then follow the route back to the bridge, often you will find tracks staying on the left hand side of the bank but this path becomes hard work, better to cross the bridge do a short climb and ski back down the ski de fond track.