ASP.NET MVC UpdateModel with a sorta complex data entry field

how do i do the following, with an ASP.NET MVC UpdateModel? I'm trying to read in a space delimeted textbox data (exactly like the TAGS textbox in a new StackOverflow question, such as this) into the model.

eg.

<input type="Tags" type="text" id="Tags" name="Tags"/>

...

public class Question
{
    public string Title { get; set; }
    public string Body { get; set; }
    public LazyList<string> Tags { get; set; }
}

....

var question = new Question();
this.UpdateModel(question, new [] { "Title", "Body", "Tags" });

the Tags property does get instantiated, but it contains only one item, which is the entire data that was entered into the Tags input field. If i want to have a single item in the List (based upon Splitting the string via space) .. what's the best practice do handle this, please?

cheers!