extended ke_search ext_localconf.php:

<?php
// ...

// register custom indexer hook for EXT:ke_search
$GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['ke_search']['registerIndexerConfiguration'][]
    = 'EXT:' . $_EXTKEY . '/Classes/Hooks/KeSearchExtenedPagesIndexer.php:KeSearchExtenedPagesIndexer';

$GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['ke_search']['customIndexer'][]
    = 'EXT:' . $_EXTKEY . '/Classes/Hooks/KeSearchExtenedPagesIndexer.php:KeSearchExtenedPagesIndexer';