I created following test.php
<esi:inline name="something">
My data
</esi:inline>
<?php
echo $_SERVER['X-LSCACHE'];
?>
<hr>
<esi:include src="something">
<hr>
<esi:include src="something">
and in .htaccess
RewriteRule test.php - [E=esi_on:1]
then from browser, access /test.php, looks working...