Ивано

$GLOBALS['TCA']['tx_sbdownloader_images']['ctrl']['searchFields'] = 'name,description,longdescription,linkdescription' ;

и так:

$TCA['tx_yourext_table'] = array(
'ctrl' => array(
'title' => 'Title of your table',
'label' => 'title',
'tstamp' => 'tstamp',
'crdate' => 'crdate',
// etc...
'searchFields' => 'title, other_field, yet_other_field',
),
);