Ajax Reply Box to Each Post on Home Page for WordPress

My Wordpress 3.01 shows the 20 full posts on the home page. I want a expandible/collapsible Ajax Reply button on each post which instantly opens an ajax reply box via which a reply can be typed and submitted to that post. Preferably the home page should not reload after submitting the comment (ajax submission) and the comment should be posted without page reload. But if this comment submission and posting without reload increases database queries on the home page loading even with WP Super Cache on, I don't mind if the home page reloads after submitting that comment but it should come back to that same post's anchor link after reloading. I want it to be done by as lightweight javascript as possible so that the speed of loading the home page is not decreased. The comments submission via this reply box should also follow the Wordpress settings which are presently set via a plugin so that comments by all below the author role (contributors and subscribers) are sent for moderation.