Tracking Disqus comments on Google Analytics

You can use that snippet just anywhere where it can be rendered on single pages. For example, you can paste this under functions.php of your theme:

function hook_disqus_config(){

if( ! is_singular() ) return;

?>
<script type="text/javascript">
    function disqus_config() {
        this.callbacks.onNewComment = [function(comment) {
            _gaq.push(['_trackEvent', 'Disqus', 'New Comment', comment.id]);
        }];
    }
</script>
<?php   
}

add_action( 'wp_footer', 'hook_disqus_config' );

Disqus should do the rest.