1. Put the file in Project:2 Reference:Site Info.
2. In Archicad, open it from the file menu. Doubleclicking it won't work.
3. In the dialog box:
Open as Archicad Project.
Create Library Parts. (Trees, for example, will be objects and are easier to replace.)
Translate.....unit into 12 Inches (ACAD & Microstation use inches)
OK.
4. You get a dialog asking where to create the library for the parts that will be created. Put this in 2 CAD Resources:2 Other Libraries.
5. If you get a dialog asking about a 'SHX' File, press skip or skip all. If you got a 'shx' with the dwg, you can use it, but it's not required. Usually they don't send it. FYI, it keeps track of font shapes and the like.
6. When the file actually opens, Save it As Filename.dwg.pln in the same place as the dwg. At this point, you don't need to open the dwg again; just use the dwg.pln.
Depending on what you're doing:
To get the topo, site boundary, trees, etc. for use in the project: Use Find & Select by layer and pen to gather up your various things. Make groups. If you sucessfully preserved the trees as objects, put the tree info in the ID field, e.g., 18" OAK. Move the stuff you want to the Archicad layer using Edit Selection Set. Copy everything and save as a 'Module from Clipboard'. Merge this into your project.
Also, you can draw with the spline tool over the dwg's contours instead of copying the 2 billion lines for each contour. You'll have to do this in Archicad anyway.
To print out the dwg to build a site model or just for the hell of it: Save the floor plan window as a PMK and place it in a Plotmaker layout.
The End.
PS: In AC8, the dwg process in slightly different, and the dialog box is very different. The basics are the same. More later.