Is it possible to call macros as part of a Visual Studio.NET command line build (or from a batch file)
Yes. You just use the following syntax:
Dev studio will start up, load the solution, run the macro and then terminate.
Be sure to check that devenv.exe is available from your command line. Normally, you just have to run VSVARS32.bat to ensure this if you do not already have this in your path.