SimpleModal Login set password at registration

<?php
/* The code below is a combination of code snippets provided by:
// Eric Martin, the creator of the SimpleModal Login plugin http://wordpress.org/extend/plugins/simplemodal-login/
// and Slobodan Manic https://gist.github.com/slobodan
// Tested, verified to work for me - Your mileage may vary.
*/
add_filter('simplemodal_registration_form', 'mytheme_registration_form');
function mytheme_registration_form($form) {
    $options = get_option('simplemodal_login_options');

    $output = sprintf('
<form name="registerform" id="registerform" action="%s" method="post">
    <div class="title">%s</div>
    <div class="simplemodal-login-fields">
    <p>
        <label>%s<br />
        <input type="text" name="user_login" class="user_login input" value="" size="20" tabindex="10" /></label>
    </p>
    <p>
        <label for="password">%s<br/>
        <input id="password" class="user_pass input" type="password" tabindex="15" size="25" value="" name="password" />
        </label>
    </p>
    <p>
        <label for="repeat_password">%s<br/>
        <input id="repeat_password" class="user_pass input" type="password" tabindex="30" size="25" value="" name="repeat_password" />
        </label>
    </p>
    <p>
        <label>%s<br />
        <input type="text" name="user_email" class="user_email input" value="" size="25" tabindex="35" /></label>
    </p>',
        site_url('wp-login.php?action=register', 'login_post'),
        __('Register', 'simplemodal-login'),
        __('Username', 'simplemodal-login'),
        __('Password', 'simplemodal-login'),
        __('Repeat Password', 'simplemodal-login'),
        __('E-mail', 'simplemodal-login')
    );

    ob_start();
    do_action('register_form');
    $output .= ob_get_clean();

    $output .= sprintf('
    <p class="reg_passmail">%s</p>
    <p class="submit">
        <input type="submit" name="wp-submit" value="%s" tabindex="100" />
        <input type="button" class="simplemodal-close" value="%s" tabindex="101" />
    </p>
    <p class="nav">
        <a class="simplemodal-login" href="%s">%s</a>',
        __('A password will be e-mailed to you.', 'simplemodal-login'),
        __('Register', 'simplemodal-login'),
        __('Cancel', 'simplemodal-login'),
        site_url('wp-login.php', 'login'),
        __('Log in', 'simplemodal-login')
    );

    if ($options['reset']) {
        $output .= sprintf(' | <a class="simplemodal-forgotpw" href="%s" title="%s">%s</a>',
            site_url('wp-login.php?action=lostpassword', 'login'),
            __('Password Lost and Found', 'simplemodal-login'),
            __('Lost your password?', 'simplemodal-login')
        );
    }

    $output .= '
    </p>
    </div>
    <div class="simplemodal-login-activity" style="display:none;"></div>
</form>';

    return $output;
}

// Add password fields for submit
add_action( 'user_register', 'ts_register_extra_fields', 100 );
function ts_register_extra_fields( $user_id ){
    $userdata = array();

    $userdata['ID'] = $user_id;
    if ( $_POST['password'] !== '' ) {
        $userdata['user_pass'] = $_POST['password'];
    }
    $new_user_id = wp_update_user( $userdata );
}

// Check password match and length requirement
add_action( 'register_post', 'ts_check_extra_register_fields', 10, 3 );
function ts_check_extra_register_fields($login, $email, $errors) {
        if ( $_POST['password'] !== $_POST['repeat_password'] ) {
                $errors->add( 'passwords_not_matched', "<strong>ERROR</strong>: Passwords must match" );
        }
        if ( strlen( $_POST['password'] ) < 6 ) {
                $errors->add( 'password_too_short', "<strong>ERROR</strong>: Passwords must be at least eight characters long" );
        }
}

// Change password e-mail text
add_filter( 'gettext', 'ts_edit_password_email_text' );
function ts_edit_password_email_text ( $text ) {
    if ( $text == 'A password will be e-mailed to you.' ) {
        $text = 'Password must be at least six characters long.';
    }
    return $text;
}

// Change sucess email text
add_filter( 'gettext', 'ts_edit_login_email_text' );
function ts_edit_login_email_text ( $text ) {
        if ( $text == 'Registration complete. Please check your e-mail.' ) {                $text = 'Registration complete, please log in.';
        }
        return $text;
}

?>