Hm, I don't know if it is doable - I think yes, but I haven't used jreviews for couple of years now.
Actually you should find a way to call this code from that tab:
require_once(JPATH_SITE . "/administrator/components/com_comment/plugin/com_content/josc_com_content.php");
return output($row, $params);
I think that this will be enough to display the comments in that tab.
Where $row should be the jreview object holding id and category information of the item and $params is the object holding the params information for jreview.
Daniel