-Add the live_comment_preview folder to bbPress' my-plugins/ directory.
-Activate the plugin in your admin area
-Add the code:
<?php add_live_comment_preview("View Preview"); ?>
to your topic.php file, where you want to show the preview's area.
ie. before the post form something like that
<?php if ( topic_is_open( $bb_post->topic_id ) ) : ?>
<?php add_live_comment_preview("View Preview"); ?>
<?php post_form(); ?>
<?php else : ?>
-Also, you can edit the CSS file (style.css) to adapt the design to your template.