MaTiZzz

Thanks. This brought me one step further to a solution.
The content I would like to target is generated in a theme specific php file (single-portfolio.php) shown here:

<div class="container clear">
        <div class="content">
            <div id="show">
                <?php
                    $args = array(
                        'post_type' => 'attachment',
                        'orderby' => 'menu_order',
                        'order' => ASC,
                        'numberposts' => -1,
                        'post_status' => null,
                        'post_parent' => $post->ID,
                        'exclude' => get_post_thumbnail_id()
                    );
                    $attachments = get_posts($args);
                    if ( $attachments ):
                        foreach ( $attachments as $attachment ):
                            echo wp_get_attachment_image($attachment->ID, 'full');
                        endforeach;
                    endif;
                ?>
            </div>
        </div>

Is there a tag so I can target images in an attachment with a post rendering hook?

Thanks!