The Name of the hill is in honor to the Pewén, which is the name in mapuzungún (language of the Mapuches) to the Araucaría, one of the sacred trees to the Pewenches (The class of Mapuches that lives in this area and which indeed means "People of the Pewén). Also the Araucaría is a Natural Monument in the Chilean law.
Another thing you need to know is that this area belongs to privates and Pewenches communities so it could be possible that when the snow melts you may see them. And actually there is a big controversy about those lands that where taken by privates years ago and Pewenches want to take back, so it could be possible you will see some Pewenches in meeting or directly protest. It is highly recommended if you go, go with a local person or directly a local guide. Please, Be very respectful in all this area.
The route itself starts as soon as you leave the forest behind and you get into the pass, you will see Cerro Los Prados on the right and the Valley that goes left to the Pewén. Depending on the snow conditions you may park before getting here.
Once you park skiing flat towards the south east in direction to the Valley where you will see the slope. Once there you have two chances: hike the flat to the slope or get into the ridge towards the forest (route marked here). Navigate throw the amazing mixed Beach and Araucaría tree forest to get into the ridge. Beside the beginning the skiing up is clear, open and comfortable to traverse.
Once on the summit choose your line and enjoy, many chances you have and specially on the lower part where you can pick up more steep downhills on the right side (looking from below).
To get back to the car you just have to manage a river crossing which you can cross by getting into a fallen tree, then just skiing flat towards the beginning.