First note: bring a bike. It's much easier and quicker.
Take the Mountain Loop Highway to Barlow Pass. Park at the pass (2,360 ft). Note: car prowls are very common here, so DO NOT leave valuables in your car. The road to Monte Cristo is not drivable to the general public and washouts from the October 20, 2003 Seattle rainstorm make this even more the case. A bicycle is nice to have and probably even recommended. The road to Monte Cristo is 4.2 miles long and gains 400 feet to the townsite (2,760 ft). Locate the trail at the far left side of the town clearing. The Glacier Basin Trail leads to Glacier Falls in about 1.2 miles. From there, the trail climbs moderately up through an annoying section of slick rocks and roots until finally leveling off. At this point the creek and trail turn sharply right to ascend past the back side of Mystery Hill. Continue about a mile to the upper reaches of Glacier Basin. You can pass the 4,500-ft timbered knoll at the center on either side. We went right. It was no problem.
Route to the North Col
From Glacier Basin take the obvious center gully through the lower cliff bands. Later in the season once the snow has gone this will be a death slog up talus. At the constriction of the gully go right around the wall above. Turn left around the backside of the wall and trudge up steep snow (to 45 degrees) for a few hundred feet to the col (6,760+ ft). The col is a beautiful place to take in the views. In particular, walk north from the col 100 feet or so to get a view of Columbia Peak through the gap to the west.
Route over to East Face
From the col, contour south on snow or possibly talus to the base of the summit cliffs. Look for a break in the cliffs offering the easiest way up. The standard route is by way of a short 5.6 chimney. It is located just around the other side of a small bulge (outcrop) in the cliff.
Beware of moat issues. The step across can be intimidating or even impossible. Also, the later in the season this climb is done, the more (lower) the snow has receded. You may need to do as much as fifty feet more of rock climbing (probably 4th Class).
Route up East Face
The 5.6 chimney is evidenced by the many aid slings dangling there and an old rusty piton (if you find it). The chimney requires three moves of Class 5 (5.6, 5.2, 5.6) for maybe 30 feet then the terrain is merely scrambling all the way to the summit. The first chimney move is right off the deck so exposure is not an issue. It requires a sort of stemming/smearing action--not the easiest thing to do in boots. The second move makes use of an indentation in the chimney. An aid sling above can be used if necessary. The third move has the leader scratching his/her way from the upper crack over a bulge to flatter ground above. Some loose handholds don't help. About 25 feet farther on there is a rappel anchor. Set up a belay here and bring up your second.
From the rap anchor a steepish ramp leads left. Snow whales may occupy parts of this ramp, their run-off slickening the slabs. The ramp ends in about 100 feet. You can rope up for the ramp but it might be just as easy to leave it at the rap anchor. Beyond the ramp the terrain is merely Class 3 scrambling for about 100 vertical feet. There is some Class 4 to be found but the rock is so shitty you couldn't place any protection anyway. The Class 4 is avoidable and/or manageable.
Downclimb the crap breccia back to the ramp. Scoot your way back down the ramp (complain to the lazy snow whales if present). Rappel back down to snow. Contour back to the North Col. Descend back to the basin. Hike the exasperatingly rocky trail back to the old townsite. Jam back out to the car at high-speed on your mountain bike. You did bring a mountain bike didn't you?
Mountain bike for the 4.2-mile road approach
Two 30m ropes or one 50m rope will suffice
A small rack (mid-sized cams for the chimney part)