A Northwest Forest Pass is required to park at the trailhead. In addition, during the winter you can only park at the highest lot if you have an Alpental skiing tag on your car. You will have to park at a lower lot and walk up, if you don't have the tag.
Approach: Summer - Hike up the main trail, until a sign designating the start of the Source Lake Overlook trail. Take this trail, which avoids losing elevation, to the valley to the south below the east face of The Tooth. There is a good climbers path with cairns to guide you.
Winter - Hike up the main trail all the way to Source Lake, then turn south in the valley. Hike up the valley until below the east face of The Tooth. Do not follow the summer path, since there is significant avalanche danger there.
The final approach involves scrambling up to the notch one south of Pineapple Pass then contouring around clockwise to get to the start of the climb. A direct scramble up to Pineapple Pass is not recommended, as this is the rappel route. The final portion of the contour around involves some class 3 to 4 scrambling, but it is short and unexposed. Some parties have elected to do a running belay here, but it is not necessary.