A new 20 page whitepaper has been published that is titled:
Using Hydraflow Storm Sewers Extension with AutoCAD Civil 3D 2008:
A Recommended Workflow
This whitepaper explains some of the basic functionality of the Storm Sewer Extension and gives some guidance on how to move data back and forth between the Extension and AutoCAD Civil 3D 2008.
If you have already downloaded the extension (available for Subscription customers only) this whitepaper can jumpstart your use of it.
If not, this paper can clarify what is being offer by the Extension.