Pass Dictionary Of RouteValues To ActionLink?

Getting to grips with ASP.NET MVC. So far, so good, but this one is a little nuts. I have a view model that contains a dictionary of attributes for a hyperlink, used like this:

menu = model variable Html.ActionLink(Html.Encode(menu.Name), Html.Encode(menu.Action), Html.Encode(menu.Controller), menu.Attributes, null) The problem is the position of "menu.Attributes" expects an object in the form:

new { Name = "Fred", Age=24 }
From what I can tell, this anonymous object is actually converted to a dictionary via reflection anyway BUT you can't pass a dictionary to it in the first place!!!

The Html generated for the link simply shows the dictionary type. How on earth do I get round this? The whole point is that its general and the controller can have set the menu.Attributes previously....

Based on a post below I tried the following:

Html.ActionLink(Html.Encode(menu.Name), Html.Encode(menu.Action), Html.Encode(menu.Controller), new RouteValueDictionary(menu.Attributes), new Dictionary<string,object>())

but this still doesn't work (I guess the code internally calls the generic method that takes objects?). The above (and my original solution of passing a dictionary to the 4th paramater produces a HTML similar to this:[URL] i.e. it's using reflection and working things out completely wrong...