How to use SSL for checkout ONLY

My zencart installation is using SSL for the entire site. I would like to make it only use SSL for the checkout, password entry, account creation, and other forms that have sensitive information.

Here are some of my config settings that may effect this.. Can anyone tell me what I am doing wrong?

  define('HTTP_SERVER', 'https://www.mysite.org');
  define('HTTPS_SERVER', 'https://www.mysite.org');

  // Use secure webserver for checkout procedure?
  define('ENABLE_SSL', 'true');

// NOTE: be sure to leave the trailing '/' at the end of these lines if you make changes!
// * DIR_WS_* = Webserver directories (virtual/URL)
  // these paths are relative to top of your webspace ... (ie: under the public_html or httpdocs folder)
  define('DIR_WS_CATALOG', '/store/');
  define('DIR_WS_HTTPS_CATALOG', '/store/');

Change this to http:

define('HTTP_SERVER', 'https://www.mysite.org');