[Jetpack] Customize the contents of the "Older Posts" text appearing when activating Infinite Scroll.

functions.php

<?php

function jeherve_custom_infinite_more() { 
if ( is_home() || is_archive() || is_search() ) {
?>
    <script type="text/javascript">
    //<![CDATA[
    infiniteScroll.settings.text = "Custom Text";
    //]]>
    </script>
<?php }
}
add_action( 'wp_footer', 'jeherve_custom_infinite_more', 3 );