We hiked in from the TeePee Trailhead, visiting the Oregon Butte tower, then north to Dunlap Spring. We took a "zero" day at Dunlap, which was actually a chance to day-hike. After that, we went south to McBain Spring, about 3 miles south of OR Butte - a beautiful spot.
Advice - stay high on the ridge - good trails. The trails in the canyons are hot in the summer and not well maintained.
The high ridge, describing a "C" shape around the Butte is fantastic - be mindful of the distance between water sources, though. Carry at least 3-4 liters.