From the Town of Silverton, drive to the east end of town where the paved road splits one block past the courthouse. Set your odometer and veer right onto blue-signed County Road 2. (On Trails Illustrated map #141 this is road #110 aka: BLM 4500.) After 2 miles, the pavement ends and the road becomes well-maintained, graded dirt. At 4.2 miles, you'll come to an intersection and the old townsite of Howardsville. Turn right onto BLM 4513 or FS589. A sign here indicates Cunningham Gulch and Stony Pass. At 4.4 miles from town, stay right. At 5.9 miles, stay right again. Do not drive up the Stony Pass Road. Continue driving south along Cunningham Creek. At about 7.1 miles is the place to park to access Little Giant Peak. At 7.6 miles is an old toilet on the east side of the road and a camp area on the west. At 7.8 miles, the good road ends, but passenger cars with moderate clearance can still make it to the trailhead. Take the right fork, drop down and cross the creek, then begin climbing on a single switchback to the trailhead. At 8.6 miles, turn left and descend sharply to cross Cunningham Creek again, (This is a low-water crossing which can be difficult in runoff season,) then drive another .2 to the limited trailhead parking area. If there's no room to park here, you can park before crossing the creek on a flat area just beyond the intersection atop some old mine tailings. Trailhead coordinates provided above are for parking at the first crossing of Cunningham Creek. The coordinates for the actual trailhead are: N 37° 46' 51.43" W 107° 34' 47.30".
At either of the two trailheads, you could park and vehicle camp overnight. On the drive up Cunningham Creek, once you pass the turnoff for Stony Pass, you can find a few other pullout type spots for an overnighter. Be careful about private property issues though. Back along CO110, there are a number of at-large, primitive sites, usually occupied by RV's and the likes. The nearest National Forest campgrounds will be either up South Mineral Creek or Little Molas Lake.
If you desire to spend more than a day in the area of the Highland Mary Lakes, then there is a short little backpack you can do to a good camp location that's only about 1.5 miles in from the passenger car trailhead or about 1mile from the 4WD trailhead. It's located in the last trees north of the lakes just above 11,670 ft., on a sloping ridge between the two main forks of the creek. There's room for several tents and a good water supply. This is where the trail to the lakes takes a decided turn to the west to follow a secondary drainage. Coordinates are approximately: N 37° 46' 10.4" W 107° 34' 34.8".