To get to the trailhead drive up Blacktail Road from Lakeside. About 3 miles after the pavement ends, you'll pass a logging road with a gate to your right. The trail begins at this point.
You'll start out with a short climb up the logging road which works as a short .25 mile warm up. At this point, you'll see the singletrack start on your left with a short but brutal climb straight up the of the trail. If you want a more gradual start just keep pedaling up the road and you'll eventually intersect the trail next to a large trail map and sign.
Either way, the rest of the climb gets easier but only a bit. Once your 2 miles in most of the steep stuff is gone except for a few bits here and there. There are few switchbacks here to even out the vertical assault so just keep fighting the rocks and grades as the trail winds up both sides of a finger that eventually makes its way to the Foys to Blacktail Trail. Keep an eye out when the trail crosses over to the southern side of the terrain feature as the views down the draw are outstanding.
Once you hit Foys to Blacktail Trail you can keep scaling the mountain up to Blacktail maximizing the trip down or start heading back early.