MFVSSW variable

 I see this can be used to 'modernize' dialog screens using unmanaged COBOL under Visual Studio.  Can it be used in a development environment?  It says to set the MFVSSW environment variable to "/c /f" , but where is this variable?  In Visual Studio?  Environmental variables under System Properties?  Is there something else we  need to get this to work?

Thanks,

Fran D.