This route description is based on a start from the lower trail head, so mileage and elevation gain will reflect that starting point. If using the Clear Creek Road trail head, you can subtract 400 feet of elevation gain. Mileage will remain about the same. Both trails join together not long after crossing Clear Creek.
From the lower trail head parking lot that can accommodate a large number of vehicles, begin hiking on the well-used and popular trail to Lower Ice Lake Basin. It's less than 2 miles into the lower basin area. The trail levels off some into the basin after a steep section of climbing on switchbacks. If backpacking into here, there are a number of good campsites in the lower basin. Not long after the trails levels in the lower basin, watch for a secondary trail turning off at these coordinates, on the right. N 37° 48' 45.33" W 107° 47' 29.55". This trail leads up first north, then west, then north again across mostly tundra to Island Lake. Beyond the lake, it actually crosses a pass NNE of the lake. Hike to the west end of Island Lake on the south side. Head NW up the basin to the saddle between US Grant and V 4. There will be a bench-like area at about 12,700 ft. In earlier season, you may have snow on this part of the ascent so ice axe and/or micro-spikes would be handy. Without snow present, you can gain this bench on mostly tundra. Above the bench, there will be an area of rock rubble to contend with, another smaller patch of tundra and then a loose scramble on talus and rubble to the saddle at 13,220 ft.
From the saddle, a direct assault on the ridge line appears difficult. To avoid those problems, try dropping down a little on the west side and then contouring below the ridge to a rock ridge followed by a loose rock-filled gully. Follow the gully up and it will top out about 100 feet below the summit on a minor north ridge of the peak. The last 100 feet along this ridge crest will be on steep, loose rubble. To gain the actual summit, you'll need to scramble over some large rocks. This peak has a split summit. The easternmost is the highest in our opinion, but just to make sure, you can scramble over tot he western summit by down-climbing a short rock face on the south side, stroll through the head of a couloir, clamber back up on more rock toward the west summit and then stroll along the ridge for the finish.
Return by the same route and if there's snow, enjoy a speedy glissade back down to Island Lake. Note: The entire Ice Lake Basin area is not only popular for its fine scenery, but also its verdant display of wildflowers. The area is very popular and receives a large number of day hikers on weekends. You will usually see backpackers camped in both the lower and upper basins.
Links to other information, routes & trip reports for this peak that may be helpful.