From the parking spot, the trail drops steeply down to a bridge crossing of Henson Creek. From there, it is close to 2.5 miles upstream and to the south, along the creek before coming to a fork. The East Fork leads to Grassy Mountain and is identified as the Grassy Mtn. trail. Take the trail to the right that continues up Alpine Gulch to the southwest. Before this junction, we found the trail to be in fairly good shape. It held most of the time to the bottom of the gulch. There are multiple crossings of the creek, at least 3 pairs, back and forth, back and forth, and so on. There is a steep climb after the first pair of crossings. Most of the crossings had logs of various sizes which seemed to diminish the further upstream we progressed. Our conclusion was that this would not be a good trail in higher runoff. The crossings would be much more difficult. None of the available maps show these multiple crossings so it's possible we were misled onto this bottom-of-the-gulch trail when the USGS map shows a trail that gains the hillside on the west and stays above the creek.
The last crossing to the east side of the creek stays on the east side until the aforementioned trail junction. It is well marked with a sign. Taking the right fork as indicated above pulls you up out of the drainage and then delivers you to a nice flat area where there would be excellent camping. The next half mile of hiking passes through stands of aspen and then your easy progress may be abruptly stopped by avalanche debris. Keep in mind, this was in 2008. A steep couloir across the creek apparently fed a strong avalanche that swept down, crossed the creek and deposited a jumble of torn, twisted and fallen trees on the east side, blocking further progress on the now becoming obscure trail. The choice here for us in 2008 was to either find a way through the tangle or drop to the west skirting along the debris path, cross the creek and then begin an ascent from there toward our summit via an intensely steep gully with lots of loose rock. We chose to head up that gully which eventually led us to the prominent east ridge of UN 13,170 and Pt. 13,084. This was a very difficult Class 2+ scramble. We don't recommend going up this way. The route we took to come down makes a far better ascent route with one caveat: if the avalanche debris is still there and obscuring the trail, then you'll have to find a way up and around that debris. Since the main trail heads up the east fork of Alpine Gulch, this trail that goes up the west fork eventually fades out. So, beyond the avalanche debris, expect to have to have to bushwhack some to continue upstream.
To continue up the gulch, work your way uphill and skirt as best you can around the debris, then drop back down in elevation some toward the creek to pick up whatever trail you can find. At the time we hiked here, we mostly found game trails that continued up the valley. Proceed up valley about .7 mile to the base of an open, east facing hillside of grass & tundra. The old trail that was once here and in use, crossed to the west side of the creek not too far past the avalanche debris. Remnants of that trail can still be seen on GE. Some coordinates for where you might want to turn up are: N 37° 58' 56.03" W 107° 23' 10.66". From this location, head generally west and uphill for 1,200 vertical feet. The drainage will split. The easier way up will be the to the left. Taking the right drainage will be a little steeper. On the way up, the trees to the south at the time of our hike harbored a number of elk. Keep heading west until you reach the SW ridge of UN 13,180, about a mile south of the true summit. The remainder of the hike north will be on mostly chiprock, small talus and rubble. It's easy walking generally and this last mile should go quickly.
For a descent, we would recommend that you return as you came, but as mentioned before, it would be possible to follow the ridge north from the summit to the prominent east ridge, then drop east down the steep gully and descend back to the creek and come out at the base of the avalanche debris, which can still preset a problem to get around. So this way probably gains you little if nothing.
Links to other information, routes & trip reports for this peak that may be helpful.