The winter closure on US 550 is one mile from the upper parking lot. At the upper lot follow the Colorado Trail. When it passes the second white rock band leave the trail to the north/right and follow the rocks for a ways, then pick through the forest towards Turkshead Peak (looks like a nipple). There's some snow in the forest but it can be mostly avoided. Once above treeline head towards the obvious saddle left of Turkshead, climbing across some snow to the top, then cross a long snow traverse towards Spencer. Once on Spencer's south ridge take a side trail to the right (marked by a small cairn) to the summit, all dry.
Gear: no special gear needed but some may want spikes and/or an axe for the snow crossing. We got by with just trail runners.