Allow at least an hour for visiting the cemetery, longer if you're a leisurely walker. 3, just east of the intersection with Rte. To get to the Jackson Shrine directly, go back into Fredericksburg on Rte. Go east on Rte. 606 until you cross railroad tracks and look for a sign on your left.
Admission is free.
Go west on Rte. 20 to Orange. From there follow Rtes. 15 and 231 to Gordonsville and Charlottesville, where you pick up I-64 west to Lexington. All the Jackson-related sites are within walking distance, so you can leave your car at the visitor center.