Directions begin from Lake City. From Gunnison, go west on SH50 to the intersection near the beginning of Blue Mesa Reservoir with SH149 and turn south. From Montrose, drive east on SH50 to the east end of Blue Mesa Reservoir for the same turnoff on SH149. Drive west and south on 149 to Lake City, just over 45 miles from the previous intersection. Once in Lake City, watch for either 3rd or 2nd street. Turning west on either will take you to Bluff St. in two blocks and a left turn (south). 2nd St. is considered the "official" access to CR20 which heads west following Henson Creek, but if you take 3rd St., it passes by a nice city park with restroom and picnic tables for those who need a break before proceeding further.
Once on CR20, drive 9.1 miles west to Capitol City on a graded, gravel road passable to passenger vehicles. On the Gunnison National Forest map, this road is labelled as BLM3303. At 5.2 miles into this drive, you'll pass the Nellie Creek Road (FR877) which accesses Uncompahgre Peak and several 13ers located in that area. At Capitol City take the right fork and continue NW on FR870 (aka: CR24) to the Matterhorn Creek trailhead turnoff at 11.1 miles from Lake City. The road becomes rougher but higher clearance SUV's and cross-overs should be able to handle to this point. Coordinates for that turnoff are: N 38° 01' 22.65" W 107° 29' 31.09". Many vehicles will choose to park here if doing Wetterhorn, Matterhorn or Broken Hill.
For Mary Alice Creek, continue driving west for another .75 mile. The road continues to get rougher and may or may not be passable for cross-over type vehicles. A stock 4WD would be a better choice for continuing to Mary Alice Creek. Park in the vicinity of the intersection for the road that turns up northwestward after crossing Mary Alice Creek. That road is the beginning of the trail up Mary Alice Creek.
In the immediate area, there is a good primitive site just before crossing Matterhorn Creek on the uphill side of the road and a couple other sites shortly after crossing Matterhorn Creek, one on the right, then one on the left. At Capitol City there is some primitive camping, but be aware of private property in that area. Then, heading west up the road to Matterhorn Creek and Mary Alice Creek, there are a few other primitive sites before reaching Matterhorn Creek. On weekends, you can expect most of these to be occupied. On weekdays, you may have your pick. There are no National Forest campgrounds along CR20 between Capitol City and Lake City.