How do I make Twenty Ten display comments on the home page?

This is something works for me. See if it works for you. Here are step-by-step instrucions:

STEP-1

In your theme’s loop-single.php, look for this:

<?php comments_template( '', true ); ?>

Replace it with this:

<?php global $withcomments; $withcomments = 1; comments_template( '', true ); ?>

STEP-2

Create front-page.php with this content:

<?php
/**
 * The template for displaying all pages.
 *
 * This is the template that displays all pages by default.
 * Please note that this is the WordPress construct of pages
 * and that other 'pages' on your WordPress site will use a
 * different template.
 *
 * @package WordPress
 * @subpackage Twenty_Ten
 * @since Twenty Ten 1.0
 */

get_header(); ?>

        <div id="container">
            <div id="content" role="main">

            <?php
            /* Run the loop to output the posts.
             * If you want to overload this in a child theme then include a file
             * called loop-index.php and that will be used instead.
             */
             get_template_part( 'loop-single' );                 
            ?>

            </div><!-- #content -->
        </div><!-- #container -->

<?php get_sidebar(); ?>
<?php get_footer(); ?>