From the intersection of Broadway (Hwy 93) and Canyon Blvd (which becomes Hwy 119 - Boulder Canyon), take Canyon west to 9th Street. Turn left (south) on 9th Street and follow that to Baseline Road (you can also reach Baseline directly from US 36 / 28th Street if coming from outside of Boulder). Take a right (west) on Baseline road, pass Chautauqua Park, and proceed to the Gregory Canyon Trailhead road (right before the road curves right and begins climbing steeply. There's a small pullout here that will accomodate 3-4 cars, or you can park at the Gregory Canyon Trailhead, along Baseline Road, or at Chautauqua Park and walk back to this point. The Flagstaff Mountain trail starts at the intersection of the Gregory Canyon Trailhead road, Baseline Road, and Flagstaff Mountain Road (which Baseline becomes as soon as it veers right and uphill).
Follow the Flagstaff Mountain Trail for approximately 1.5 miles, 1300 feet, and 6(!) road crossings to the intersection of the Flagstaff, Range View, and Ute Trails. Take a left on the Ute Trail, walk approximately 100 yards to an old jeep trail on the right. Turn right and follow this up to the highest pile of rocks in the lightly forested meadow.
Descend via the same route or make a loop hike out of it by following the Ute trail to the Gregory Canyon trail and back to the Gregory Canyon Trailhead.
Typical Front Range dayhiking gear will suffice. This is a pretty mild trail and makes a nice after-work trail run.