From the center of Randle take the road signed "Mt. Adams" and drive 1 mile south to a split. Veer left on road #23, and follow it for about 32 miles. Turn left on road #2329. At 5.7 miles arrive at the trailhead for the Killen Creek Trail, about 4600'.
Follow the Killen Creek trail for three miles to the intersection with the PCT. Go north for about .25 mile then turn uphill following boot tread through meadows and rock slides. Arrive at a large meadows with stunted krumholz at about 6900'. Good base camp possibilities here, and plenty of water.
Ascend the prominent north ridge here, following the crest as much as possible. When confronted with a series of gendarmes, resist the temptation to pass them on the east (it will dead end), and instead drop down onto scree and pumice slopes on the west. Then scramble back up to gain the ridge.
The ridge will now take you directly to the summit plateau, with snow as steep as 40 degrees in places. Ice axes are mandatory, crampons will probably be needed, and a rope may be useful to string as a hand line in a few exposed places.
The summit plateau is almost a mile across, and you will arrive on the wrong side. Walk south to the snow pile that marks the roof of the sulphur miner's cabin to stand on the true summit. [Editor's note: check the map for the location of the true summit -- I don't think it is at the shack. -Mike]
Follow the climbing route.
Trip report with pictures: http://home1.gte.net/mandm/adams-9307.html