Enable login with user id or email in Drupal 6

Email Login with D6

/**
 * Implements hook_form_alter
 */
function trnAccount_form_alter(&$form, &$form_state, $form_id) {
  global $user;

  switch($form_id) :
    case 'user_login':
      // build the validators array
      $validators = array('trnAccount_login_validate') + user_login_default_validators();
      // override default validators
      $form['submit']['#validate'] = $validators;
      break;
  }
}

/*
 *	uberacchount_login_validate
 *	Created by: mandelbro
 * 	Login validation handler which enables login with either id or email
 */
function trnAccount_login_validate($form, &$form_state) {
  global $user;
  // get the mail from from_state values
  $mail = $form_state['values']['name'];

  // check if the name field is an email address
  if(!valid_email_address($mail)) return; // no need to move forward

  // query the user table for the email
  if($name = trnToolkit_get_var("SELECT name FROM {users} WHERE mail = '%s'", array($mail))) {
    // if we found a username, swap it for the email in form_state values
    $form_state['values']['name'] = $name;
  }
}