As the (yet non-official) maintainer of Shell as a CPAN distribution, I would like to defend there are good uses for Shell. But this does not seem one of them: all of the external programs you are calling have Perl builtins or core libraries to do it portably and faster.

use Shell qw( perl ); # { local @ARGV = (...); do $filename; } 
use Shell qw( dir );  # glob() seems enough
use Shell qw( copy ); # File::Copy
use Shell qw( del );  # unlink
use Shell qw( cd );   # chdir
[download]

All the advices of the monks who replied to this node still apply. Some refactoring and moving filenames and tasks to configuration metadata driving the script could produce a much more robust and useful tool. But probably this isn't a priority or a need. So just two suggestions: (1) use / everywhere because Perl at Windows understand it very well unlike Windows itself; (2) maybe the Perl scripts "d:/perl/macc1" and "d:/perl/mmac3" can be converted to Perl modules with advantages to maintenance.