Carbondale head south going towards Redstone. Turn at the first pullout on the left for the town of Redstone (the northern-most). After passing the fire station, slow down and start looking for a dirt road on the left leading into the aspens. It's really a nondescript dirt road, so if it looks really well used, it's not the one.

Per chris deulen: go through Redstone (follow the signs). Immediately outside, there's a sign (and a parking lot, on the right, none on the left, mind you) that says, "Redstone Boulders." Park here. Go back to the right 20 feet and take the road up to a trail on the left. Then follow directions as described by Kirk. You can't miss the trail on the right that goes up mountainside. Go past the first boulder to get to the Stein Boulder.

Per Kai DeLorenzo: the GPS coordinates are: 39.18786287225547, -107.23418028669461. It's very close (20-40 feet) to the intersection of East Creek Trail and Redstone Boulevard.