Styling/hacking "comments" div

Hi

I’d like to style the <div id="comments"> on a page (not post)

The aim is to create a “Customer suggestions page” with:

1. Respond form loading in lightbox (i use Prettyphoto to do this)
2. Approved “Suggestions” (i.e. comment list for that page) appearing beneath intro paragraph and styled accordingly

To achieve (1.) I have written the following function which I’ve yet to get to work

function yourideas_comments($content) {
if (is_page('18')){
$content = str_replace('<div id="comments">', '<div id="inline-ideas" class="pp_inline clearfix" style="display: none;" id="comments">', $content);
   return $content;
}
}
add_filter('xxxxxx','yourideas_comments');

PLEASE HELP if you can!

Cheers!
(If its of any importance I’m using a Thematic Child theme)