See the Getting There section of the main page and take the road as far as you can until it ends.
From your car, head south on the "road" as it narrows and becomes a gravel trail. The trail is overgrown in areas but not hard to follow. After about .3 miles you it will widen again and you will come to the Beachie Saddle. There is a small sign on a tree ahead of you that points the way to the Mt. Beachie Trail. Look back to your right and you will see another similar sign on a tree that says Battle Ax Trail. Take this as it switchbacks up the side of the mountain for about a mile and a half to the summit. There are some cool rock formations on the way and great views on a clear day of the Cascade peaks.
Total distance is about 1.85 miles with 1600 feet of elevation gain.
None needed but no water on the trail.
If you have information about this route that doesn't pertain to any of the other sections, please add it here.