$conditions = array(
    'Tweet.text LIKE' => '%aa%',  //implied and
    array( //implied and
        'or' => array(
            array('Tweet.text LIKE' => '%11%'),
            array('Tweet.text LIKE' => '%22%'),
            array('Tweet.text LIKE' => '%33%'),
            ...
        )   
    ),
    array( //implied and
        'or' => array(
            array('Tweet.text LIKE' => '%123%'),
            array('Tweet.text LIKE' => '%456%'),
            array('Tweet.text LIKE' => '%789%'),
            ...
        )   
    )
    'not' => array(
        'or' => array(
            array('Tweet.text LIKE' => '%x%'),
            array('Tweet.text LIKE' => '%y%'),
            array('Tweet.text LIKE' => '%z%'),
            ...
        )   
    )
)