[Plugin: Background Manager] Override getOverrideID

I would like to overide the function, without writing to de plugin it selft,

Why: Because in my homepage I show the lastest post, and i what to show its background, instead of the default one.

protected function getOverrideID($meta, $orig_data)
    {
        global $post, $wp_query;

        $id = false;

        // Is this page being used as the post_as_page?
        if ($wp_query->is_posts_page)
            $id = (isset($wp_query->query_vars['page_id']) && $wp_query->query_vars['page_id']) ? $wp_query->query_vars['page_id'] : $wp_query->queried_object_id;

        // Otherwise, if it's just a regular page/post or the home
        if (!$id && is_singular()){
            $id = $post->ID;
        }

        // Still nothing, then don't bother
        if (!$id)
            return $orig_data;

        $post_specific_data = get_post_meta($id, $meta, true);

        if ($post_specific_data == -1) {
            return 0; // Disable
        } else if (!$post_specific_data) {
            return $orig_data; // Default
        } else {
            return $post_specific_data; // Override
        }
    }

to

protected function getOverrideID($meta, $orig_data)
    {
        global $post, $wp_query;

        $id = false;

        // Is this page being used as the post_as_page?
        if ($wp_query->is_posts_page)
            $id = (isset($wp_query->query_vars['page_id']) && $wp_query->query_vars['page_id']) ? $wp_query->query_vars['page_id'] : $wp_query->queried_object_id;

        // Otherwise, if it's just a regular page/post or the home
        if (!$id){
            $id = $post->ID;
        }

        // Still nothing, then don't bother
        if (!$id)
            return $orig_data;

        $post_specific_data = get_post_meta($id, $meta, true);

        if ($post_specific_data == -1) {
            return 0; // Disable
        } else if (!$post_specific_data) {
            return $orig_data; // Default
        } else {
            return $post_specific_data; // Override
        }
    }

http://ww.wp.xz.cn/extend/plugins/background-manager/