Why
With the first four peaks in Cascades North being activated, I decided I needed to hatch a plan to hit the next two. This summit is over 7 miles from the nearest trailhead and 3300 feet of gain, and it's 4000 feet of gain from our trailhead, so I recommend doing it as an overnight. We activated this peak in conjunction with North Cinder, W7O/CN-006, and I strongly recommend if you put in the effort to do one that you make time for the other. This is a wonderful set of peaks, if you are looking for a pleasant backpacking trip with a very manageable day hike. If you want to hike 15 miles with 4000 feet of gain for a single summit, you could summit it in a day, but that's past the limits of my endurance. I prefer this as a backpacking trip.
Getting there
I planned this trip as a two-night backpacking trip with KJ7FXU, with two nights at Swallow Lake. We started from the Marion Lake Trailhead, but you can do it from Cabot Lake Trailhead or approach from Pamelia Lake if you like. To get to Marion Lake Trailhead, proceed 16 miles past Detroit on OR-22 E, and turn left on Marion Creek Road, which goes 4.4 miles to the trailhead. This is a popular trailhead, and a Discover Pass is required. Also, in season, a Central Cascades Wilderness Permit.
The hike:
Day 1
Marion Lake Trail is well-used and well-maintained. Starting from Marion Lake, these trails are quite well maintained and popular. We saw some people between the trailhead and Marion Lake, even in late September. As you hike you will proceed through beautiful, dense forest, to boulder fields and vine maple, and eventually to cattails and reeds as you approach Ann Lake. You may encounter some signs indicating a campfire exclusion zone for a quarter mile in all directions from Ann and Marion lakes. 
Marion Lake in the evening. You will come to Ann Lake after a mile and a half; hike along it and continue towards Marion. After 1.7 miles from the trailhead, you get to a fork marked with a sign saying Marion Lake Trail to the left, and Marion Lake Bypass to the right. Continue to the left, and in .3 miles, again choose to go left instead of taking the Marion Lake Bypass. Another .4 miles will lead you up and away from the lake, along a creek bed (which may have a creek in it in spring and summer), where you come to a sign marking the fork for Lake of the Woods or Lake of the Woods Trail. Take this, and proceed up a good trail through the woods, which start to thin and then break into a complete burn only starting to reforest. In this burn, there is a signpost at the turn for Swallow Lake Trail, which sends you up the hill to your right, heading east. 
Entering the burn area. Swallow Lake Trail is a 4-mile, lightly traveled and middling-poor maintained trail, I expect especially so late in the season. There were several logs that forced other hikers to divert and create a trampled path around them, and several newly downed trees. I would recommend having GPS as a backup, but we were always able to see and follow this trail, although it was not always obvious. I recommend this for groups with at least one experienced hiker only. It was also frequented by groups with pack animals. At half a mile, you will pass Sad Lake, but you won't see it or know it's there except by looking at your map, and there are no clear trails to it. At a mile from the trailhead, the trail bears south, and more-or-less levels off; at two miles, it turns east again and starts to climb to the PCT and South Cinder. After the first pair of loose switchbacks here, there is an unmarked trail heading towards the lake. These switchbacks are accurately represented on CalTopo, and the easternmost one pointing towards the lake is the one that has a path leading to it. It's less than a quarter mile to the lake. 
Our campsite for the night, right on Swallow Lake. There are several opportunities for water along this trail, both at Marion Lake and at creeks and lakes along the way, but in September the creek from Swallow Lake was a thin trickle which might have been filtered and the next creek did not even have puddles. Sad Lake and Swallow Lake are easy to access, though, and had water. After this point, the next opportunity for water is past North Cinder, although there are several lakes far below the PCT which are marked and clearly visible from it.
Day two
The second day we proceeded up the trail to South Cinder. This portion is reasonably easy to follow, and after about 600 feet of gain breaks into the open and climbs the cindery scree of the cone. It enters and climbs a gully between South Cinder and a small prominence to its south, and proceeds up towards a small meadow, turning slowly more north, until only what amounts to a ditch lies between you and the cone of South Cinder. 
The trail is gouged by water; during rain this is likely to become a stream. 
This is less than a quarter mile from where we turned to climb. We turned left, crossed the ditch, and proceeded directly up the cone where it was free of trees, consisting of scree and loose small-to-medium rocks, but a trail exists a little further to the north; this might be easier to hike, and we took it on the way down. From the lake, to the established trail to the summit, to the peak, is 1500 feet of gain and about 1.7 miles; cutting onto the cone only saves a sixth of a mile each way. 
Ascending the cinder cone. If you are done here, you can head back to the lake, having done a moderate and short hike, pack up your tent, and head out; if you are proceeding to North Cinder, you continue down that path, and I will describe my approach in a North Cinder article.
When you get there
You will have unbelievable views, both climbing to the cinder cone and once you get there. This peak climbs away from the forest and gives you magnificent views of the burn that occurred, showing patches of complete burn and patches of complete forest survival. You will also have magnificent and close views of Three Fingered Jack, and once you crest the mountain, an absolutely breathtaking view of Mount Jefferson from a uniquely close position, as well as unobstructed views in all other directions. There are a few scrubby trees at the summit, but from various points you can see in every direction that Mount Jefferson doesn't obscure. 
View from the ridge, most of the way up, facing south-east. Three-Fingered Jack features prominently. 
Jefferson came into sight, so suddenly and strikingly that I yelped. We had plenty of contacts on 2m, getting K7ATN on low hills in the Coast range and working stations on several mountains in Washington, as well as plenty of contacts from Bend, Redmond, and Prineville. I was using a 3-element yagi, but we were able to work some stations with a whip. I didn't even bother getting HF out on this summit. You may not have as many stations on other summits, but we also didn't stick around very long; any other summits in the area should hear you easily.
