Start at Willow Lake Trailhead and hike up the trail to Willow Lake. Skirt around the north side of Willow Lake and follow the light trail as it leads you above the cliff and the waterfall. This is a good place to set up a base camp.
From the cliffs above Willow Lake proceed Willow Creek. Up the valley you will see a cliff face and a large pile of truck-sized boulders below the cliff face. You can either stay along the creek and pass below these boulders, or you can contour along Challenger’s north face and pass above the boulders and below the cliff face. I believe staying low is probably easier and faster but it doesn’t make that much difference.
Once past the boulders ascend toward Kit Carson’s summit. If you passed below the large boulders this will mean ascending a talus slope. If you passed above them this will mean negotiating some class two gullies. Ascend up a ways until you have cleared the cliff band. You will see some grassy ledges off to your right (west). Make your way onto the grassy ledges and ascend these until the grassy ledges give way to class-4 climbing.
Initially the ridge starts off as more of a face, but it gradually sharpens into a very sharp ridge. When the ridge becomes prominent you will want to be right on it. If you need to stray from the ridge proper your best options are usually to the right (west side). A climber we met during the ascent said that you could easily get into real trouble if you stray to the left of the ridge (east side). For the remainder of the climb Barry and I stayed within fifteen feet of the ridge proper and spent most of our time right on it.
The next 1,500 feet or so is sustained, airy, class-4 scrambling. The exposure is invigorating and the scrambling challenging. About a hundred yards from the summit the ridge flattens out and the remainder of the ascent is a relatively flat, class-2 scramble to the summit.
Although the rock is mostly very solid, there is a little bit of loose stuff. Therefore a helmet is a good idea. Otherwise just bring your standard gear for hiking in the mountains.