A substitute for ExpandoObject in .NET 3.5 with least overhead-Collection of common programming errors

How can I imitate the functionality of the ExpandoObject in a .NET 3.5 application with the least overhead? My best lead so far is to use the Lin Fu framework ( http://www.codeproject.com/KB/cs/LinFuPart2.aspx ), but I’m thinking there may be something better.

To give a better idea of what I am going for here, my objective is to dynamically create the type from the parameters of a MethodInfo. So, basically I want to turn this:

    public class ServiceObject
    {
        public void Execute(string TransformMeIntoAProperty);
    }

into

    public class ServiceObjectExecuteSignature
    {
        public string TransformMeIntoAProperty{ get; set;}
    }

at runtime. I have to be able to access the Parameters using Reflection, because I am using Linq Expressions.