Start parked at the trailhead where the bathroom is. Skin or hike up the trail following the standard route
which is a road up into the basin. You'll pass a series of signs at the upper trailhead with information signs and a sign in log. Keep going, and you'll see what looks like Sneffels on the right, but it is a false summit. Continue around this to the left and you'll be able to see Sneffels once you pass this gnarly summit.
Once you are at the base of Sneffles, Lavender Col.
is the huge, somewhat steep snow slope that heads up to the saddle on the right of the mountain. At the saddle, look left and follow the much steeper upper Col. to the summit. Be careful at the top of this steep Col. because a large cornice changes over the other side, and if you walk up to look around the corner you could fall. Instead, about 30' below the top of the Col. head left over the rocks and this will take you to the summit.
Ice axes are recommended for the upper Col., especially if the snow is hard. Crampons will also be required, so be careful if the snow is hard - people die up there. If you fall in the upper Col., you'll keep going to the base of the entire mountain without an effective arrest.