Casting an object to underlying interface using late bound calls

hello,

I have a function that will take 2 parameters, the first is an object and the second is a string that represents an interface that has been implemented by the passed in object. 

I do not know in advance what this interface string will be, or the object type that is passed in.

I want to cast the object to the passed in interface (assuming it has been implemented).

If I new the interface I wanted this is very simple with say "Return CType(Obj, InterfaceName)"

In this example "InterfaceName" is a passed in string - how can I acheive this converstion using this string?

Thanks

Matthew

matvdl