The Van Horn Park route follows old, well-defined logging roads and is well marked with signs and blue diamonds. There are, however, several confusing junctions, and finding the trailhead can be trying. If you start from the Hunter Creek Trailhead you'll soon need climbing skins, so put them on before you start.
For travel from Aspen to the hut, leave from the Hunter Creek Trailhead. Ski a fairly level trail NE through scrub oak 1/8 mile, then across the Benedict Bridge over Hunter Creek. From here the trail climbs steeply for 3/4 mile on the south side of Hunter Creek, then breaks out into an open area at 8,600 feet elevation. Continue NE through lower angled open areas for 1/4 mile, then turn N and cross the 10th Mountain Bridge over Hunter Creek (8,640 feet). This bridge is well marked and easy to spot, but could be elusive in poor visibility. In that case, stay close to the stream past 8,600 feet elevation and you'll bump into the bridge.
After you cross the 10th Mountain Bridge, continue N for a few hundred feet, then make a climbing traverse W (downvalley) to within sight of a sturdy fence and private home. Staying about 100 feet E from the fence, begin climbing N again and you will intersect a clearly visible snow-covered (or possibly plowed, see below) road at about 8,720 feet. Follow the road as it takes a 1 1/3 mile climbing traverse to Lower Van Horn Park at Lenado Gulch. Take care not to turn left into Lenado Gulch. Just continue on an easterly tack across Lower Van Horn Park, through a gate (usually open), then climb NE through another aspen forest into Van Horn Park—a classic alpine "open space."
The road just past the 10th Mountain bridge over Hunter Creek may be plowed, thus being an unpleasant walk. For better backcountry atmosphere take the following alternate route: After crossing the footbridge, take a route marked with blue diamonds on bamboo poles, which heads up the valley paralleling Hunter Creek. About a mile from the footbridge the route swings N and climbs several switchbacks of foot-trail to intersect the plowed road at a higher point just before Lower Van Horn Park at Lenado Gulch. Walk the road a short distance to reach Lower Van Horn Park, then continue with the directions above to reach Van Horn Park.
Read your map with care and ski up the north side of Van Horn Park to Lower Van Horn Saddle (really just a low-angled shelf) at 9,760 feet. Continue along the north side of the park to Upper Van Horn Park, then Upper Van Horn Saddle, a more definitive saddle at 9,925 feet, just E of point 10,097. From Upper Van Horn Saddle, ski easterly up a well-marked, narrow road-cut through the forest. This road gradually climbs 2 miles to the McNamara Hut. Generally, this trail is easy to follow. If you happen to catch it unbroken, use your compass and altimeter, and take care to not drop N down into the dense timber and steep terrain of the Woody Creek drainage. You'll usually smell wood smoke before you see the hut, as it is hidden by trees until you are within a few hundred feet.