Winter and spring ascents are done occasionally, especially by ski mountaineers. The normal route is the west face via the Halfmoon Creek Trailhead.
It seems like the west face of Massive is actually very seldom visited in winter due to the long distance to get there in winter. The east face route is actually the normal route in winter, and can be approached from more than one direction.
One route is from the Fish Hatchery, and in winter, this may be the most used route. Another route is to follow the closed road from the closure to the summer trailhead and climb the standard Colorado Main Range Trail. The shortest option seems to be the route up Willow Creek.