If you have an iPhone search for "Mountain Directory East and West" in the app store. A great app!
Pay more attention to the downhill than the uphill! That app will tell you the slowest curve on the downhill side.
At the top determine your target max speed for the downhill run.
Start down in the appropriate gear for that speed, but 5 to 10 MPH below your target. Use your engine brake if you have one.
Let the speed build until you reach your target speed, then brake firmly to drop down 5 to 10 MPH, then release the brakes and don't touch them again until you get back up to your target speed.
Repeat as necessary.