Hike or drive to the Montezuma Basin parking area at 12,800. TH info on main page.
You will probably want to put your crampons on here.
There are no route finding difficulties. It is obvious and completely visible from the uppermost basin.
From the 4x4 parking hike to the uppermost basin between Castle and Conundrum under their connecting saddle. Stay to the left side. Soon the couloir comes into view. It is the obvious, continuous couloir leading straight up to the northeast ridge a hundred feet or so below the summit.
Simply climb straight up to the ridge. Keep an eye out for rockfall. There was very little while we were there. If the fall line was directly down the gully, the run out would be okay. However it is angled just enough that slides would likely send the climber into the wall/talus/scree piles. Better than flying off a cliff but not something you want to happen so be careful.
Maximum angle is 40 degrees.
Once on the ridge climb up the ridgeline the short distance to the summit. Great views here. Depending on snow cover, there may be one tiny rock outcropping but it poses no problem - just pass on through it.
The usual and easiest return is to descend to the Castle - Conundrum saddle and begin a series of glissade/hike cycles back down to the 4x4 trailhead. You won't need your crampons for the hiking parts so stow them securely at the top.
Another descent option is to ski down the couloir.
This is a basic snow climb requiring ice axe and crampons in addition to one's normal 14er kit. I recommend helmets as well. Bring rope and protection if makes you feel comfortable but it really is not necessary for anyone but the inexperienced or timid.