BuddyPress.org

This is what I do. You can add this in your theme, in mu-plugins or in bp-custom:

function rk_signup_redirect() {

if (strpos($_SERVER['REQUEST_URI'], 'wp-signup.php') !== false ) {

$url = 'http://ryuuko.cl/register';

wp_redirect($url);

exit;

}

}

add_action('init', 'rk_signup_redirect');

You should change the url to fit your needs, or use a redirect in .htaccess.