From the parking walk through to the start of the ski de fond track, follow this over the bridge and then west uphill on the ski de fond track. At the top of the slope you pass a small shrine, not far after this a path leads south and zip zags up the hillside. This summer path (red dotted path on the map) continues all the way to the col, in winter you follow it but make sure you don’t cross the torrent de la Lauze (this is the more obvious path) as this will lead you to the wrong area.
Please note that on my map and GPX it doesn’t go to the col it finishes a short way before it on a ridge, this was due to poor snow conditions the day I did it, but from there you can see the col and it’s not hard to navigate.
There are many options for going down; you can follow your route up as best as you can or you can head down through the trees to the north. I have run down through the trees many times and as always with tree runs I have found great routes with open spaces, and also been shut down by the trees closing in and had to bush bash. On my map and GPX we were too far to the west and found the going hard so I would suggest being to the east of that track. At the bottom of the run you meet the ski de fond track, once on that it’s a skin or pole back to the little shrine and back to the parking.