There are several ways to approach Cedar Mountain, but none of them are easy. You can no longer begin at Bonneville Hot Springs or park under the powerlines(waypoint below).I recommend parking at the Bonneville Trailhead on highway 14 and biking to the power lines below Aldrich Butte. It's 2 flat easy miles. You can throw your bike in the bushes.
Start your hike from Bonneville Hot springs. They charge 10$ to park there, but this greatly reduces the mileage, otherwise you have to park at the Bonneville Dam trailhead on highway 14. Take the Dick Thomas trial to the Aldrich Butte trail, then the Cedar mountain trail. You will cross the lovely Cedar Creek and climb a steep path up 1000 feet, to the flower filled meadows on the the summit. At the top you will enjoy great views westward of Hamilton Mountain, Hardy Ridge and the Gorge. Expect solitude! Cache is an ammo can. No need to go back down that steep trail. You can make your trip a loop: just continue north from the summit and come up the spine of the next un-named ridge to the PCT at the Westway Trail junction (there is a cache there by Paul DK). Then you will get a fast 3 mile downhill return via the PCT to the Aldrich Butte road (aka Moffett Creek road on some maps).