public class SuperBase
{
	protected virtual void SomeVirtualMethod()
	{
		...
	}
}

public class Base
{
	protected override void SomeVirtualMethod()
	{
		...
	}
}

public class MyClass
{
	protected override void SomeVirtualMethod()
	{
		// ЧТО ДОЛЖНО БЫТЬ ЗДЕСЬ, ЧТОБЫ ВЫЗВАТЬ SuperBase.SomeVirtualMethod?
		// НАДО ЧТО-ТО ТИПА 
		// base.base.SomeVirtualMethod()
		// но так не работает.
	}
}

SuperBase o = (SuperBase)this;
o.SomeVirtualMethod();

		protected override void AddAttributesToRender(HtmlTextWriter writer)
		{
			base.AddAttributesToRender(writer);
			if(ImageUrl.Length >  0 )
			{
				writer.AddAttribute(HtmlTextWriterAttribute.Src, ResolveUrl(ImageUrl));
			}
			if(AlternateText.Length >  0 )
			{
				writer.AddAttribute(HtmlTextWriterAttribute.Alt, AlternateText);
			}
			if(BorderWidth.IsEmpty)
			{
				writer.AddAttribute(HtmlTextWriterAttribute.Border, "0");
			}
			if(ImageAlign != ImageAlign.NotSet)
			{
				writer.AddAttribute(HtmlTextWriterAttribute.Align, Enum.Format(typeof(ImageAlign), ImageAlign, "G"));
			}
		}

protected override void AddAttributesToRender(HtmlTextWriter writer)
		{
			writer.AddAttribute(HtmlTextWriterAttribute.Type, "image");
			writer.AddAttribute(HtmlTextWriterAttribute.Name, UniqueID);
			if(Page != null && CausesValidation)
			{
				if(Page.Validators.Count >  0 )
				{
					writer.AddAttribute(HtmlTextWriterAttribute.Onclick, Utils.GetClientValidatedEvent(Page));
					writer.AddAttribute("language", "javascript");
				}
			}
			base.AddAttributesToRender(writer);
		}