To get to the trailhead you have to approach from the west side of Death Valley. You need to get to the Panamint Valley which is east of Hwy 395. You can head up from the Ridgecrest or Hwy 190 from near Lone Pine. This is sesert so fill your tank before leaving Hwy 395. There aren't a lot of roads out here so getting lost would be hard to do. You want to get to Wildrose on the west side of Death Valley. When I was there the road from near Stove Pipe Wells to Wildrose was closed. You have to come in from the west. The roads are paved to Wildrose although not very well once you leave the junction of the road between Panamint Springs and Trona.
Follow the signs to Mahogany Campground from Wildrose. The Wildrose Guard Station was closed when I was there and it doens't look like it is occupied very often. The gravel road is good up the hill to the charcoal kilns and then it gets rocky with ruts. High clearance vehicle is a must.
The Telescope Peak trail is well marked once you get to Mahogany Campground. Don't follow the road up to the communication towers on top of Rogers Peak. This will only add elevation to your total climb and you will have to go cross country back down tothe trail on the south side of the peak.
The sign at the trailhead says it is 7 miles to Telescope Peak, but my GPS measured the distance at 6.35 miles. Total distance is 12.3 miles with 3,300 ft of elevation gain. It took me almost 5.5 hours on a beautiful clear day in August.
The trail passes Rogers Peak on the east and then Bennett Peak on the west before heading upt he ridgeline and several switchbacks to the summit of Telescope. The trail is easy to follow. The summit of Telescope is actually behind the highpoint that you have been looking at as you hike up the trail.
Water, sunscreen, hat, and good shoes in the summer. In the winter, come prepared for blizzard conditions