TYPO3 pages/pages_language_overlay erweitern - ext_localconf

/***
 * pages-Tabelle Erweitern
 */
// Elemente 'slide'-bar machen
$GLOBALS['TYPO3_CONF_VARS']['FE']['addRootLineFields'] .= ',tx_extendtest_background_image';

/***
 * pages_language_overlay-Tabelle Erweitern
 */
$TYPO3_CONF_VARS['FE']['pageOverlayFields'] .= ',tx_extendtest_background_image';[/php]

Und im TypoScript habe ich dann schon so einiges versucht:
[typoscript]page.5 = COA
page.5 {
    5 = TEXT
    5 {
        wrap = -Field: |-
        field = tx_extendtest_background_image
    }
    10 = IMG_RESOURCE
    10 {
        wrap = -IMG_RESOURCE: |-
        file.import = uploads/pics/
        file.import.data = tx_extendtest_background_image:-1,slide
        file.import.override.field = tx_extendtest_background_image
    }
    20 = TEXT
    20 {
        wrap = -TEXT: |-
        data = tx_extendtest_background_image:-1,slide
        override.field = tx_extendtest_background_image
    }
    30 = TEXT
    30 {
        wrap = -TEXT2: |-
        data = levelfield:-1, tx_extendtest_background_image, slide
        override.field = tx_extendtest_background_image
    }
}