I still need to get a procedure for how to theme Map data in Civil 3D, Map 3D or Land Desktop, but at least I can give you how to get it in your drawing.
There is a pdf in the files area of the Yahoo Group files area of the Yahoo Group . You have to join to get it, but everyone is welcome to join.
This procedure will help you bring GIS data into Map 3D, Civil 3D, or Land Desktop versions 2004 through 2007. (2004, 2005, 2006, 2007) There are a few minor interface changes between 2004, 2005 and 2006, but this should look pretty normal for all of those versions.
This procedure brings in ESRI Shapefiles, ArcInfo Exports, ArcInfo Coverages and Microstation .dgn files.
Remember that Civil 3D 2007, Land Desktop 2007 and Map 3D 2007 can also reference these files as well as import them.
Check out post You Can't Do That in CAD, Can you?! Referencing GIS data...