Note: UN13,028 would be an easier and shorter climb if combined with Milwaukee and Pico Aislado on a backpack trip to the Sand Creek area. Unfortunately, when we climbed those other two summits in 1995, we were not even considering going on to climb all the 13ers, leaving UN13,028 as a "hanging or orphaned peak" as we call them. This required us then to find another route and so it made the most sense to us to combine it with our climb of Crestolita. There is an excellent description of the Milwaukee/Pico/13,028 climb on LoJ by looking under any of those peaks. The traverse from Pico Aislado to UN13,028 is described as Class 2. We have included a photo in the UN13,028 gallery of the connecting ridge for those considering an approach from Pico. If using that approach, we would recommend the return route also described on LoJ that drops you off UN13,028 to the small lake WNW of the summit and dropping down into Cottonwood Creek, locating the trail that returns one back east to "Milwaukee Pass" and then returning to your starting point in the Sand Creek drainage.
Route from Broken Hand Pass: From the end of the access route at 11,000 ft on South Colony Creek, follow either of the two trails to South Colony Lake and proceed up the trail to Broken Hand Pass as described for Crestolita. From the pass, drop about 200 feet in elevation on the trail to Cottonwood Lake and watch for a trail to the left (south) that contours over to the Broken Hand/Crestolita saddle. (Alternately, if climbing Broken Hand, drop straight from the summit to the same saddle on mixed tundra and scree and rock.) Enjoy the amazing view of Crestone Needle from this saddle. From the saddle, continue south on lush grass and tundra losing about 350 feet elevation to a flat, marshy area with several reflective, small tarns. From this location, obtain a view down into Cottonwood Creek below and aim for near the last group of trees you see and for a break in the willows surrounding the creek. From the tarns, begin a steeper descent punching your way through willows and dense evergreens, avoiding short cliffbands and rocky outcrops as best you can, while dropping down steep chutes at times. Cross the creek near a beautiful waterfall on some large boulders and once across, contour somewhat uphill for half a mile to the small but beautifully situated lake at just above 11,800 ft., WNW of the UN13,028 summit.
From the small lake, we had first assumed we would have to climb more directly south to the saddle between the 12,795 point and 12,989. But as we headed that direction, we found a series of tundra benches that led us upward, first SE, then east toward the ridge north of the 12,989 point. The benches led to some steep tundra ramps and higher up the tundra finally gave way to rubbly rock. Once on the main ridge, easily walk NE, then east over broken rocks and rubble to the summit. Enjoy an amazing view of the Crestones, Crestolita, Pico Asilado, Music Mountain, etc. To return, basically reverse your route. Doing this summit alone will require nearly 4,600 feet in total elevation gain for the day. Combining with Broken Hand and/or Crestolita will possibly add another 1,000 ft.
Links to other information, routes & trip reports for this peak that may be helpful.