Summit:
W7O/NE-010
Unless you're in extremely good shape (or just crazy) Sentinel Peak should be done as a backpack trip. The best way to activate is to hike to Aneroid Lake along the E Fork Wallowa Lake Trail (1804) starting at the Wallowa Lake TH.
To get to the Wallowa Lake TH drive to Joseph, OR and continue South on hwy 351/Powerhouse Rd. Once near the southern end of the lake take a left to stay on Powerhouse Road and follow it to the end. Parking is free and you do not need a NW Forest Pass for this TH.