I climbed neighboring Kelso Mountain on 2/13. So not current info for you, but maybe useful? This is for the "main" Stevens Gulch route.
The road is not driveable at all unless you have a snowmobile or snow cat. You will have to start at the highway and hike it. Adds 5-6 miles RT from summer. I did not need snowshoes on the road though. From the summer trailhead there was a packed trail, but it was getting windblown over. Snowshoes were used, and probably necessary. The avy slopes on Kelso can be easily avoided by staying wide of them in the flats. The route was well wind packed (solid snow, but very firm), and postholing was minimized to a handful of willow traps. Try and follow old tracks if you can, I was following an old skin track when it wasn't blown in with snow.
I left the trail at the Kelso/Torreys saddle, so the rest is just from visual notes. The trail above was snow packed, with some windblown talus the upper part of Grays. The trail that splits to the saddle is all snow and possibly slide prone, you have to climb higher than normal to connect to Torreys. You will have to partially reclimb Grays to avoid this slope when descending from Torreys. I have done both in winter before and usually the connecting ridge is fairly windblown and mostly talus.