Well it is possible but then you need to create custom coding in this case. What you need to do here is - make a callback_insert where you pull out the data submitted - set it into a session and return true.
add the following code into your controller
$crud->set_lang_string('insert_success_message',
'Your data has been successfully stored into the database.<br/>Please wait while you are redirecting to the list page.
<script type="text/javascript">
window.location = "'.site_url(strtolower(__CLASS__).'/'.strtolower(__FUNCTION__)).'";
</script>
<div style="display:none">
'
set it to whatever page you want. This will allow you to redirect to specific page post sucessful insert. On other page - retrieve data from session and display with confirm button and so on and on click of confirm button, write the code to fetch data from session and store it into the database. - DONE. But with this, you defying the use of GC as for adding the data (Your call)