WordPress.org

Installation is pretty standard:

i.e.

1. Upload comment-author-checklist.php to the /wp-content/plugins/ directory
2. Activate the plugin through the 'Plugins' menu in WordPress
3. Place <?php if (function_exists('show_comment_author_checklist')) show_comment_author_checklist(); ?> inside the Loop in the template file of your choice (usually single.php).

Example: <?php the_content(); ?>