public static MvcHtmlString RenderLabelFor<TModel, TValue> (
    this HtmlHelper html,
    Expression<Func<TModel, TValue>> value,
    object htmlAttributes
) where TModel : class
{
    TagBuilder builder = new TagBuilder("td");
    builder.MergeAttributes(new RouteValueDictionary(attributes)); // to convert an object into an IDictionary
    builder.InnerHtml = LabelExtensions.LabelFor(html, value).ToString();
    return MvcHtmlString.Create(builder.ToString(TagRenderMode.Normal));
}

public static MvcHtmlString RenderLabelFor<TModel, TValue> (
    this HtmlHelper<TModel> html,
    Expression<Func<TModel, TValue>> value,
    object htmlAttributes
)
{
    ...
}