At the trailhead parking, you really have two good options. Your choice will be based primarily what you prefer - a longer trail hike or a steeper bushwhack of sorts. The Guide to the Colorado Mountains had the directions that we basically followed. Option 1 will take you from the trailhead down toward the main south fork of Treasure Creek, following Trail # 710. This trail heads south, staying above the creek on its west bank, then it switchbacks to the NNW and makes a broad arc to the west to intercept the Continental Divide trail # 813 near the bottom of the east ridge of Summit Peak. The advantage of this approach is that it utilizes trail the entire way to the east ridge and ascends more gradually. The disadvantage is that it adds significant mileage. Option 2, suggested in the book above, is more direct, has more vague trail to follow thus requiring some route finding skill and starts out much steeper.
For Option 2, look for a trail heading up alongside the western fork of Treasure Creek that drains the basin below Summit, The Unicorn and Montezuma. The trail climbs very, very steeply, staying just on the north side of the creek. Initially, after a few hundred yards, it passes by an attractive waterfall and pool that's difficult to reach but easy to view. The trail tended towards being faint in 2010. Above this waterfall, the trail eventually crosses the creek as the book indicates somewhere above 11,400 ft. On the other side of the creek, we found one pink ribbon tied to a nearby tree affirming our route. (Likely no longer there.) Once across the creek, the forest begins to open up. Continue hiking west and contouring south until Summit Peak comes into view (rather unmistakable). As you round a broad tundra ridge, you should encounter the well-used trail #710 and begin following it south. This trail will lead past the west side of the 12,400 ft. closed contour and then will intersect the Continental Divide trail coming in from the south of Summit Peak, and near where the steep part of the east ridge begins. In the tundra-filled basin below Summit, we spotted a nice group of cow elk and their newborn.
The eastern ridge of the peak drops off through some rocky outcrops with a couple of penetrating gullies that lead up toward easier terrain above. You can take a more direct approach heading directly up one of these two gullies or swing around to the south side of the east ridge and contour your way up along the ridge on largely tundra slopes that steepen. On the east ridge, higher up, you may want to take numerous photos because of the spectacular shots that keep presenting themselves. The remainder of the hike up this peak is steep but negotiable, tundra-covered terrain with some embedded rock. From the summit, the north ridge that connects to The Unicorn and ultimately Montezuma appears problematic, but it's not. The views of this stunning southern Colorado landscape are stunning with vast, tundra and forest-covered vistas stretching out in all directions. With our visit in 2010, the forest here was still quite healthy. We would not be surprised to learn however that by this point, much of it has been beetle destroyed because the infestation in southern areas of Colorado is so great.
Links to other information, routes & trip reports for this peak that may be helpful.