I found where I should modify the script (tribe community events class) but would like to know if a hook in functions.php would work to send the user to /login instead of generating a login form (any code examples for this newbie would be appreciated :).
// login check
if ( ( !$this->allowAnonymousSubmissions && !is_user_logged_in() ) || ( $edit && $tribe_event_id && !is_user_logged_in() ) ) {
do_action( ‘tribe_ce_event_submission_login_form’ );
$output .= $this->login_form(__( ‘Please log in first.’, ‘tribe-events-community’ ));
return $output;
}