Access by car from Colmar: take the western bypass around Colmar, then the D417 (or the slower but more scenic D10), pass through Munster, take the D10, pass through Metzeral, Sondernach, take the D27, then the D430 (route des crêtes), pass through Markstein, turn right onto the D27, and arrive at the Ferme-auberge du Treh.
Park in the car park.
(S/E) Depart from the Ferme-auberge du Treh, heading north, along the red-white-red marked trail (towards the Ferme-auberge de Steinlebach).
(1) Cross the D27 and continue along the trail. This joins a path that you follow to the right (northeast) and leads to the Route des Crêtes (D430).
(2) If you follow the red-white-red markings, you will leave the path and take a trail that leads directly to point 4 and then to the Steinlebach farmhouse inn, but these markings are often difficult to see and you will end up at point 3, on the D430 (route des crêtes).
(3) At point 3, take this road to the right for about 100 metres (watch out for vehicles, especially motorcycles).
(4) Follow the large green sign for the Steinlebach farmhouse inn and continue towards the Steinlebach farmhouse inn on a small paved road.
(5) At the entrance to the Steinlebach farmhouse inn, turn right at an acute angle and follow the signs for the south-west (red triangle markings). Cross the Steinlebachrunz stream. This small section is wet and the stream may flood the path. Go through the ski slopes, under the ski lifts, then next to a water treatment plant. Immediately after, turn right to pass the Notre-Dame des Neiges chapel and arrive at the Markstein station.
(6) Pass the start of the summer toboggan run and cross the Route des Crêtes (D430) to reach the D27.
(7) Cross the road and after about 50 metres, turn left (north-west) onto a pretty path that goes through the forest. Keep your distance from the D27 on your right. This will take you to the Ferme-auberge du Treh (S/E).
It is of course possible to start the hike from Markstein (large car park, very touristy, do not leave valuables in your car) or from the Steinlebach farmhouse inn.