The name for trail #1996 is "The Lost Man" trail. It has two access points off Highway 82 out of Aspen. The first access is 14 miles east of Aspen and is a large parking area on the north side of the highway, across from the Lost Man Campground. This section of the trail leads up to South Fork Pass and Lost Man Lake. If accessing the Williams Mountains, this is the shortest and easiest access.
The other access point is 18.5 miles from Aspen, still on Highway 82, at the last switchback before the final climb to the top of Independence Pass. This access, I am calling "The Roaring Fork River" trailhead to distinguish from the Lost Man TH. Parking here is on the north side of the highway at the switchback. Parking is limited here and fills quickly on weekends. If coming from the east slope, you'll need to drive north from Buena Vista or south from Leadville and turn west on Highway 82, drive past the Twin Lakes and continue to the summit of Independence Pass. Drive down west from the summit and the trail head will be at the first switchback you come to.
Most at-large camping along the west side of the Independence Pass road has been shut down, but there are several Forest Service, fee type campgrounds out of Aspen. They are in order starting from the farthest from the TH: Difficult Creek, Weller, Lincoln Gulch and Lost Man. If you're coming from the east slope, you're best off camping at any number of at-large spots on the east side of Independence Pass, in the upper regions of Lake Creek. We like the Graham Creek area where a diversion tunnel comes out and empties into Lake Creek.
From the trailhead at highway 82, head north up the well used trail #1996 that goes to Independence Lake, following along the creek. In a short distance, a trail forks to the left, just after crossing a creek, that leads up to Linkins Lake. Don't turn onto that one. Continue on up valley, following the trail which crosses back to the east side of the creek after a while. This trail passes through many willows. The old trail on the west side of the creek that the USGS map shows going to a pass between the two Geissler peaks is no longer in use. Continue hiking along the main trail with plenty more willows and then turn off at a sharp bend where the trail turns east to gain some elevation. This is about 1.1 mile from the start and just above 12,100 ft. Leave the trail and hike NW over lush and wet tundra toward Geissler West. Aim for a nice looking, tundra covered slope that leads to the ridge just south of the summit. The hike up to the ridge is an easy walk. Once on the ridge, turn north and scrambled over or skirt some rocky obstacles that guard the summit. Time to this summit is under two hours.
From the summit, you have a nice view of the Williams Mountains to the west. From Geissler West, the traverse over to Geissler East is a fairly easy task. You might as well include it in your day unless you're already dodging lightening bolts by this point.
Links to other information, routes & trip reports for this peak that may be helpful.
Mountain Handbook ›Geissler West(Requires free registration & login to view)