Here's a map I put together some time ago. I don't claim to know everything, and Ulysses lives up there, so listen to what he says and don't take what I say as exhaustive. That said, here's the map:
http://caltopo.com/m/1J35If you're coming up from the west, I think the easiest routes to follow (no trail mind you) are the "HJ" route and the ridge route. The "HJ" route is a route I scouted a few years back. It's one drainage south of the drainage that Deer Springs flows down. It's much easier than following up the Deer Springs drainage (steeper and more brush) which I've labeled the "Norris" route. The ridge route is also fairly easy to follow.
DO NOT (in my opinion) try the Middle Fork of Stone Creek. If you're coming from the Deer Springs Trailhead, it's tempting to cut up early to Marion, but there's brutal brush and major boulders. You've been warned.
The easiest route in terms of steepness is to go all the way to Owls Hooch campsite in LRV and then cut up over Drury Saddle into the summit plateau country. Then just contour along at about 10,100 feet until you get to the foot of Marion. Least amount of steepness, least amount of brush, but the greatest number of miles. I sometimes like to go up either the ridge or HJ routes and come down the Owls Hooch route. Makes a nice loop albeit a fair number of miles.
HJ