seperating ipv6 and ipv4 traffic

[Ryan B]

server {
        server_name secure.mydomain.com;
        listen       443;
        gzip         on;
        gzip_comp_level  1;
        gzip_types      text/plain text/html text/css
application/x-javascript text/xml text/javascript;
        gzip_static on;
        gzip_http_version   1.1;
        gzip_proxied        any;
        gzip_disable        "msie6";
        gzip_vary           on;
        ssl          on;
        ssl_ciphers RC4:ALL:-LOW:-EXPORT:!ADH:!MD5;
        keepalive_timeout  0;
        ssl_certificate      /root/server.pem;
        ssl_certificate_key  /root/ssl.key;

           location / {
                root   /var/www;
                index  index.html index.htm index.php;
            }

        }

Seems to work well (and accepts both SSL ipv4/ipv6 since they point to
same ip)..
But I'd like to move ipv4-only traffic away to another ip. How is this
done? I'm guessing I create 2 of these, specifying ipv4 in one and
ipv6 in the other?