The Les Houches ski area has become very popular for uphill skiers training on or near the pistes.  The route described below avoids most of the crowds and is suitable for bad weather days when the higher hills are out of condition.  The ascent follows one of the summer mountain bike tracks for most of the way, signposted  "Col de Voza" if not buried.  The descent of the E face and a small section of the ascent is avalanche prone, so care is needed.

Ascent

Drive past the bottom Prarion lift station and take the road towards La Maison Neuve.  After a few of hairpins, there is a road coming in from the right, (leading to the "Ecole de Physique" and Charousse.)  Parking is possible at this junction.  Walk along the road for about 100m to the "Amis de Nature", from where a path, (or a road just beyond) is the start of skinning.  It is possible to reach this same point from the end of the Prarion parking by go up through fields, past newly built holiday homes.
Follow the road until it turns sharp left into a chalet.  At this point go straight on (steep a first) into the forest, past a chalet on the on the right to Granges des Chavants, where you join the track coming up from Charousse.  The track curves back left to a chalet and then narrows and winds its way up through the forest, traversing right to overcome a little steep section before turning back left.  At a signpost turn right to go up more steeply, just to the right of a vague spur  After about 20 to 30mins from the last chalet, the forest changes from being predominantly coniferous to being mostly deciduous. There is a cairn about 1.5 metres high, (snow dome) on the left.  Just above this the track turns left and descends a few metres before traversing more or less horizontally leftwards, (careful this section is avalanche prone,) to come out underneath the Prarion bubbles.  Here you join the signposted uphill ski track, (red signs).  Follow this track until you come out of the forest and onto the piste coming down from Prarion top station, just above the bottom of the "Table d'Orientation Ski tow.  In Feb 2013 the pisteurs modified the "official track".  Just before you exit the forest there is a red signpost pointing up hill, still in the woods.  Follow the track, red and white/yellow ribbons tied to trees, all the way to the top of the Prarion bubble lift.  Alternatively, at the first exit onto the piste go straight up its right hand side if it is not busy, (more direct).  From the Prarion top station, (1845m) go along the S ridge of the Prarion, initially sign posted for snowshoers, over the "Petit Prarion", (the snowshoe track turns off to the left here,) and continue along the ridge, (one steepish section) to the three summits.  Excellent view point.

Descent

The classic ski descent is by the E face,(S3) starting from the shoulder between the Prarion and the Petit Prarion.  Go down the open slopes trending rightwards looking down, to avoid the worst of the bushwacking/little cliff "drop-offs"  Eventually you should join your ascent tracks.  Facing E it gets the morning sun and can quickly become avalanche prone and/or transformed, (heavy) snow.
If in doubt return the way you came to the top Prarion station and ski down the pistes.  Or better, ski down the W face, through the trees and then skin back up, (or take the Chamois ski tow,) to the top Prarion station.
It is also possible to complete the traverse of the Prarion by going down to Col de la Forclaz.  However, the traverse is probably best done in the other direction. (See "Prarion from Chatelard" route routes/315268/fr/le-prarion-depuis-le-chatelard)