Thanks to everyone for their tips.  I'll let you know how things
develop.  It sounds as if using Andreas's gcc tool chain is the path
of least resistance (I assume that's where the references were
pointing, and I've already downloaded it). 

PhiHo, thanks for the useful equivalences for MSVC.  And you're right,
blowing away the files in the project and then repopulating it is
probably much safer and easier.  The thing I'm thinking of writing
would be a script, probably hanging off the .dsw file.  It sounds as
if creating a project file from all the *.c files under vm would be a
useful first step.

Finally, I should add for the record that I tried to build all the
plugins as internal in my first attempt.  And while exporting the
symbols is necessary, I guess (even for internal plugins?), obviously
MSVC has its own idiom for it.  I vaguely recall it's
Redmond-specific--big surprise.