You can specify the filename for downloading using the "Content-Disposition" header. Like this:

#!/usr/bin/perl -w

open (ZIP, "test.zip");
binmode(ZIP);
@all = <ZIP>;
close(ZIP);
print "Content-type: application/zip\n";
print "Content-Disposition: filename=test.zip\n";
print "\n";
foreach (@all) {
    print;
}
[download]