Select only one role on registration form

Perhaps there is some relevant code in the OG Registration Format module:
http://drupal.org/sandbox/madmatter23/1287462

This module will let you change the format of the 'Groups' field on the User Registration form to:
Checkbox (default)
Select List
Autocomplete Textfield

Has anyone figured this out? Did OG Registration Format help? I was close with https://drupal.org/sandbox/wolmi/2022403.
However the checkbox from role delegation is still there for users without the admin toolbar

<?php
function one_role_form_alter(&$form, &$form_state, $form_id){
    switch($form_id){
        case 'user_register_form':
        case 'user_profile_form':
            $form['account']['roles']['#type'] = 'radios';
            $form['account']['roles']['#required'] = TRUE;
            foreach($form['account']['roles']['#default_value'] as $key => $default){
                if($default != 2){
                    $form['account']['roles']['#default_value'] = $form['account']['roles']['#default_value'][$key];
                }
            }
            break;
    }
}

/**
 * Implements hook_user_presave()
 * Hack for registration & profile forms, attaches the authenticated role
 */
function one_role_user_presave(&$edit, $account, $category) {
    if (isset($edit['roles'])) {
        $edit['roles'] = array ( $edit['roles'] => $edit['roles'], 2 => '1' );
    }
}
?>

HI I use a JQuery script and checkboxes in "user.module" line 1127. WORK!

$checkbox_authenticated = array(
    '#type' => 'checkbox',
    '#title' => $roles[DRUPAL_AUTHENTICATED_RID],
    '#default_value' => TRUE,
    '#disabled' => TRUE,
  );
  unset($roles[DRUPAL_AUTHENTICATED_RID]);
   $form['account']['roles'] = array(
    '#type' => 'checkboxes',
    '#title' => t('Roles'),
    '#default_value' => (!$register && isset($account->roles) ? array_keys($account->roles) : array()),
    '#options' => $roles,
    '#access' => $roles && user_access('administer permissions'),
    DRUPAL_AUTHENTICATED_RID => $checkbox_authenticated,
  );
  echo '<script src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
  <script>
  $(document).ready(function(){
  	$("#edit-roles input").change(function(e){
  		console.log("changed");
		var i = 0;
  		$("#edit-roles input").each(function(){
  			if(i == 0){
  				i++
  			} else {
	  			$(this).attr("checked",false);
  			}
  		})
		console.log(e)
  		e.currentTarget.checked = true;
  	})
  })
	  </script>';
  $form['account']['notify'] = array(
    '#type' => 'checkbox',
    '#title' => t('Notify user of new account'),
	'#default_value' => TRUE,
    '#access' => $register && $admin,
  );

This ticket is very old, but for anyone who comes across it, take a look at
https://www.drupal.org/project/single_user_role