I've read the thread, and it seems that you still are
looking for an answer. You don't seem to want to use
the built-in AutoCAD exporter, so it seems you really
only have one avenue left.. to extract from the .dwg
file yourself using VBA.

Have you ever opened a .dwg file using, say, Notepad?
(BTW, I'm familiar with AutoCAD and Lisp, but not since
DOS days, so I can't help you with file structure).
The .dwg file is undoubtedly a huge text file, albeit
possibly with many non-printable characters.

My question is -- is the file understandable? Can you
see the data  you are looking for? I assume it is something
like a list of room, with dimensions -- or something of
that ilk. If so, you could create a "parser" using VBA.
Just create a loop to read the file line by line.. skip
over lines that are not of interest; parse the ones that
are.

Does this help you get started?