Finally a fun peak! See my CR for "S 3" for approach information. "S 4" looks like an insane peak from basically every angle but it's quite a bit easier and way more fun than it looks. On the south face locate a red scree gully. It will be on the western half of the peak and is the only red gully on the south face. "Climb" up it as best you can, it's very loose. Microspikes might be helpful. The gully constricts then opens up again; after it does so, head left to the ridge crest. At first the ridge is simple and consists of climbing along ledges and over ribs covered in broken rock. At one point you'll traverse on an upward ledge on the north face. To this point the ridge is only Class 2+. Eventually you'll approach a steeper section with a pile of rock mashed into a chimney. To get to the bottom of the chimney either squeeze through a very narrow slot or climb a short (10ish feet), slabby wall to the bottom of the chimney, then carefully pick your way through the rocks in the chimney. They were surprisingly stable but there were huge gaps that you could fall into should things shift or you slip or something. I don't know how you'd climb back out if you fell into one of the holes. Climb up the chimney as exposure north increases and then scramble back to the ridge crest. The remaining route is Class 2 with maybe a couple moves of Class 2+, but beware as the ridge is narrow in spots, down sloping, extremely exposed north and south, and covered in small dinner plate-like rock. It's not hard, just airy. Reach the summit and enjoy the amazing surprise up there. We reversed our route down and wore microspikes on the gully descent (did not wear them on the ascent). Extremely fun peak and absolutely worth the time and effort!
Photos (click for slideshow):