Post a comment from site to facebook?

Hi all,

I have written a comment system for a client, and he has also asked that users can click a checkbox which allows for the comment to be shared with facebook - something like the comment box at the bottom of this page:-

Now ive done some googleing, and I found this :-

But this uses facebooks own comment system, which I dont want to use. I was wondering if anyone could tell me kindly, what if any are my options?

Kind regards and thanks,