This is one of the classic alpine traverses in Colorado (similar to the N. Arapahoe to Navajo traverse, Little Bear to Blanca traverse, Crestone Traverse, etc.). The route sees little traffic, so solid route finding skills are essential. The entire route goes at low 5th class if you stay on the ridge itself, otherwise, there are 4th class options to avoid spines by moving down from the ridge.
You can either start at Mayflower Gulch or McCullough Gulch. The most logical is to start from Mayflower off of US 91 (Copper to Leadville road). If approaching from Mayflower, head northeast and gain the north ridge of Fletcher. From the top of Fletcher, examine the ridge and begin your adventure.