The easiest way to do this is to override the woocommerce_breadcrumb function. Add something like the following to your functions.php (obviously add whatever changes you want to make to the markup in the appropriate places):

// Customize the WooCommerce breadcrumb
if ( ! function_exists( 'woocommerce_breadcrumb' ) ) {
    function woocommerce_breadcrumb( $args = array() ) {

        $defaults = array(
            'delimiter'  => '<span class="divider">Delimiter</span>',
            'wrap_before'  => '<ul class="breadcrumb visible-desktop">',
            'wrap_after' => '</ul>',
            'before'   => '<li>',
            'after'   => '</li>',
            'home'    => null
        );

        $args = wp_parse_args( $args, $defaults  );
        // Don't display on product single page
        if (is_singular('product')) { } else {
            woocommerce_get_template( 'shop/breadcrumb.php', $args );
        }
    }
}