Start by parking at Dutchman Flat Sno-Park, which is located just opposite to the base area at Mt. Bachelor. If you're doing this adventure during the summer, late spring, or early autumn you should be able to follow the Tumalo Mountain hiking trail all the way to the top. However, if you're visiting during late autumn, winter, or early spring there is most likely still snow covering the ground. This was the case when I did the hike, if so, you can start straight up the side of the mountain from the parking lot.

There should be tracks in the snow from other hikers that are easy to follow, which will lead you in the right direction (just follow the most worn path). Eventually you should reach a large open area with very few trees, just short of the summit. From here, you can choose basically any route to get to the top of the mountain. Total elevation gain of the hike is approximately 1200 feet. Enjoy the view!

Summit coordinates: 44.00530°N, 121.6428°W