I was never able to get AJAXed Wordpress to do what me (and apparently the questioner) want to do.
I use a custom solution that makes use of a plug-in called Inline Ajax Comments. I had a heck of a time finding a download link, but here's one that still works: http://kashou.net/files/inline-ajax-comments.zip
In WordPress' theme editor, I edit index.html. After the following:
<?php the_content(''); ?>
I add (after enabling the plug-in of course):
<?php ajax_comments_link(); ?>
<?php ajax_comments_div(); ?>
I then edited the plugin PHP file itself. I commented out blocks of code as follows:
if ($comment_count == '1') {
echo('<span id="show-inline-comments-'. $id .'"> ');
/* echo('<a href="javascript:;" id="show-inline-comments-link-'. $id .'" onmouseup="ajaxShowComments('. $id .', \''. $throbberURL .'\', \''. $commentpageURL .'\'); return false;">show comment »</a>');
*/
echo('</span>');
echo('<span id="hide-inline-comments-'. $id .'" style="display: none;"> ');
/* echo('<a href="#comments-'. $id .'" onmouseup="ajaxHideComments('. $id .', \''. $throbberURL .'\', \''. $commentpageURL .'\'); return true;">« hide comment</a>');
*/
echo('</span>');
} else if ($comment_count > '1') {
echo('<span id="show-inline-comments-'. $id .'"> ');
/* echo('<a href="javascript:;" id="show-inline-comments-link-'. $id .'" onmouseup="ajaxShowComments('. $id .', \''. $throbberURL .'\', \''. $commentpageURL .'\'); return false;">show comments »</a>');
*/
echo('</span>');
echo('<span id="hide-inline-comments-'. $id .'" style="display: none;"> ');
/* echo('<a href="#comments-'. $id .'" onmouseup="ajaxHideComments('. $id .', \''. $throbberURL .'\', \''. $commentpageURL .'\'); return true;">« hide comments</a>');
*/
echo('</span>');
}
IIRC, that's all I had to do, but let me know if that doesn't work for you. I'm trying to reverse engineer my own solution since it seems to be exactly what you want to do as well.