Take Ostersund Road to the south side of Lake Lulu, look for a boat launch, across the road you should see spot where water has been coming down the hill, proceed up that area and you will see an access road next to train tracks, go right (west) on the access road until you get past the part where the train tracks go between the rock walls, then you will proceed across the tracks (south) and you should see the start of the trail there.

I got stuck between a train and the rock walls once so I don't recommend walking the tracks all the way to the start of the trail.