Cannot use memcache for sessions and cacherouter for cache tables

I would like to use memcache module to store users' sessions in memcache and cacherouter module to store cache tables in memcache (or elsewhere).

My configuration in settings.php is thus like this:

/* Use custom session handling via memcache */
$conf += array(
  'session_inc' => './sites/all/modules/memcache/memcache-session.inc',
  'memcache_servers' => array(
    'localhost:11211' => 'default',
  ),
  'memcache_bins' => array(
    'session' => 'default',
    'users' => 'default',
  ),
);

/* Use custom cache handling via cacherouter */
$conf['cacherouter'] = array(
  'default' => array(
    'engine' => 'memcache',
    'servers' => array('localhost:11211'),
    'shared' => TRUE,
    'prefix' => '',
    'path' => NULL,
    'fast_cache' => FALSE,
    'static' => FALSE,
  ),
);

The problem is that when authcache module finds memcache_servers among the variables, it infers that it should use memcache.inc as cache manager.