use Env '@PATH';
my @short = map {Win32::GetShortPathName($_) }  @PATH;
print 'set path=', pop @short, "\n";
print "$_\n" for map { "set path=$_;%path%" } reverse @short;

__END__

...
set path=C:\PROGRA~1\GNU\GnuPG;%path%
set path=C:\PROGRA~1\gnuwin32\bin;%path%
...