If you have some secure pages located at:
/big/dom/xdomain/www/Secure_Server/mystore
Then you can provide a symbolic link to this are from the non-secure area:
cd /big/dom/xdomain/www
ln -s Secure_Server/mystore mystore
Now "mystore" is available in NON-SSL mode using this URL:
http://www.mydomain.com/mystore/
or in SSL mode:
https://secure.mydomain.com/mystore/
Note that you cannot create a symbolic link from within the secure area to somewhere outside it as this would break the SSL connection.