There are vba samples that ship with the product. They are at C:\Program Files\Autocad Civil 3D 2008\Sample\Civil 3D API\VBA\
If you search this discussion group as well as the base product you will find samples. Also the Autodesk University website has some good stuff on it.
Christopher
http://civil-3d.blogspot.com/
Civil Reminders
http://blog.civil3dreminders.com/
http://www.CivilReminders.com/
Alumni