How to Add Confirmation email field in magento registration form using class validate-cemail?

The following method allows you to add confirmation email address field in your customer registration or newsletter page.
Create a javascript file called validation.js under "js/email/validation.js"

Validation.addAllThese([

    ['validate-cemail', 'Please make sure your emails match.', function(v) {
                var conf = $('confirmation') ? $('confirmation') : $$('.validate-cemail')[0];
                var pass = false;
  var confirm;
                if ($('email')) {
                    pass = $('email');
                }
  confirm =conf.value;
  if(!confirm && $('email2'))
  {
  confirm = $('email2').value;
  }
                return (pass.value == confirm);
            }],
]); 

Add the new js file into your customer.xml file

On the register form add a new field to contain the email confirmation field "template/customer/form/register.phtml".

*CONFIRM EMAIL
 

Thats all. You are done.