How to get values out of object HtmlAttributes

you can transform the object htmlAttirbutes to an attribute/value string representation like this :

var htmlAttributes = new { id="myid", @class="myclass" };

string string_htmlAttributes = "";
foreach (PropertyDescriptor property in TypeDescriptor.GetProperties(htmlAttributes))
{
  string_htmlAttributes += string.Format("{0}=\"{1}\" ", property.Name.Replace('_', '-'), HttpUtility.HtmlAttributeEncode(property.GetValue(htmlAttributes).ToString()));
}

PropertyDescriptor belong to the class System.ComponentModel

I usually do something like this:

   public static string Label(this HtmlHelper htmlHelper, string forName, string labelText, object htmlAttributes)
    {
        return Label(htmlHelper, forName, labelText, new RouteValueDictionary(htmlAttributes));
    }

    public static string Label(this HtmlHelper htmlHelper, string forName, string labelText,
                               IDictionary<string, object> htmlAttributes)
    {
        // Get the id
        if (htmlAttributes.ContainsKey("Id"))
        {
            string id = htmlAttributes["Id"] as string;
        }

        TagBuilder tagBuilder = new TagBuilder("label");
        tagBuilder.MergeAttributes(htmlAttributes);
        tagBuilder.MergeAttribute("for", forName, true);
        tagBuilder.SetInnerText(labelText);
        return tagBuilder.ToString();
    }

I suggest you to download the ASP.NET MVC source from the codeplex and take a look at the built in html helpers.