Just tried the simple simple version of your script (shown below) using both ModPerl::Registry and ModPerl::PerlRun. Both worked as expected. I could download myarchive.zip from my apache server without any trouble.

Perhaps you could share more details on what isn't working?

use Archive::Zip::SimpleZip ;

print "Content-Disposition: attachment; filename=\"myarchive.zip\"\r\n
+";


my $z = new Archive::Zip::SimpleZip '-', Stream => 1;

my $fh = $z->openMember(Name => "myarchive.zip");
print $fh "hello world\n";
close($fh);

$z->close();
[download]