From the Spanish Creek TH hike up the Spanish Creek basin to 11,800 feet.
The South Couloir from Spanish Creek also leads to the same 13,620 foot saddle as the Outward Bound Couloir.
from 11,800' turn north and climb the deep couloir east of the Prow. The couloir leads directly to the 13,620 foot saddle between Kit Carson and Columbia Point. Just below the saddle look for a cairn or two marking the start of the traverse to Columbia. It is not particularly obvious but it should not take too long to find. Note that far below the saddle is another cairned route. I suspect this leads up another gully and intersects with the traverse but that is little more than a guess.
Anyway, find the start of the traverse and begin climbing steeply under the impossible looking SW face.
The whole traverse is cairned but most are small and the route is somewhat convoluted. In dry weather the route is moderately exposed scrambling. Keep your eyes open and your wits about you.
The traverse ends just below and slightly to the SE of the summit.
Roach's guidebook makes the traverse section seem easier and only rates it a 2 but I would rate it class 3. The traverse might be pretty sketchy with snow and ice. If you have first hand snow experience please post your knowledge.
Ice ax and crampons. Not recommended outside of snow season.