Bill, it's been a few years since I've made the trip, but basically there're two ways to get to the east portal. Drive up Chalk Creek west from Nathrop (basically you follow the old roadbed) past St Elmo and all the way to the old townsite of Hancock. From here, you hike the roadbed a few miles to the portal. The road to St Elmo is graded Forest Service road. Above St Elmo it's a bit rougher. 4wd is generally not needed, but it'll be easier in a vehicle with good ground clearance.
The other option is to drive to the west portal and make the hike over the top. The route is easy to see, but it is a climb at high altitude, so be prepared.
There's not much to see at the east portal, but if you've an interest in the old South Park, you should make the trip at least once.
Scott