Referera till SiteMap i IHttpModule

I princip är det detta jag vill göra:

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

namespace Henrik
{
	/// <summary>
	/// An IHttpModulemodule implementing site-wide description meta-tags.
	/// </summary>
	public class MasterPageModule : IHttpModule
	{
		public void Init(HttpApplication context)
		{
			context.PreRequestHandlerExecute += new EventHandler(context_PreRequestHandlerExecute);
		}
		private void context_PreRequestHandlerExecute(object sender, EventArgs e)
		{
			[b]Page page = HttpContext.Current.CurrentHandler as Page;[/b]
			if (page != null)
			{
				page.PreLoad += new EventHandler(page_PreLoad);
			}
		}
		private void page_PreLoad(object sender, EventArgs e)
		{
			Page page = sender as Page;
			if (page != null)
			{
				HtmlMeta meta = new HtmlMeta();
				meta.Name = "description";
				[b]meta.Content = SiteMap.CurrentNode.Description;[/b]
				page.Header.Controls.Add(meta);
			}
		}

		public MasterPageModule()
		{
		}
		public void Dispose()
		{
		}
	}
}

Men hur får jag del av min SiteMap i detta sammanhang?