Gregg,
This may be too late. M. Murray's Trout Fishing in the Shenandoah National Park does not include Passage Creek. His other book Virginia Blue-Ribbon Streams: A Fly-Fishing Guide does list Passage Creek. Per this book, the northernmost part of the creek flows through GW National Forest and a Virginia DWR WMA and has excellent access. He specifically mentions turning onto Crisman Hollow road from State Route 675. The junction is about a mile west of Camp Roosevelt. Note, Crisman Hollow road is about an 8 mile long seasonal NF Service Road, supposedly suitable for passenger cars (YMMV). I don't know if the state stocks this upper section or not.
He also mentions downstream access at the Elizabeth Furnace Campground. State Route 678 (Fort Valley Rd) parallels the creek from the fish hatchery upstream to a few hundred yards past Elizabeth Furnace where it becomes private land. I've fished that a few years ago. I seem to remember there were pull-outs sporadically spaced along both sides of the road. The hatchery is at the intersection of 678 and 619. It was closed for renovations when I fished the creek. There was a parking spot or two near the hatchery back then.