It sounds like you want to wrap everything starting with the first HR and ending with last.
Following will wrap everything between the two HR and then remove them( my interpretation of your question).
var $start=jQuery('.content-container-wrapper hr:first-child'),
$end=jQuery('.content-container-wrapper hr:last-child');
$start.nextUntil( $end).wrapAll( '<div class="working">');
$start.add($end).remove();
You can't insert part of an element and then insert the end the way you do in a text editor
API reference: