This isn't a very scalable approach, and has a dirty feel to me:

if ($roll_your_own == 1) {
    $ENV{'CONTENT_LENGTH'} = length($cgi->query_string());
    open(CGI, "|a_different_script.cgi") or die($!);
    print CGI $cgi->query_string();
    close(CGI) or die($!);
}
[download]

In its favor, it should pass all of the arguments it receives, and it does so without letting them be evaluated by the shell.

Update: I noticed that the CONTENT_LENGTH value is not necessarily accurate in the receiving script. Reset it before opening the pipe.