How to use AjaxContinuation in FubuMVC

LogOn.spark

<script>
$(document).ready(function() {
		$("#btnSubmit").click(function(e) {
			e.preventDefault();
			$.ajax({
				type: "POST",
				dataType: "json",
				url: "log-on",
				data: $("#logonForm").serialize(),
				success: function (response) {
					/* when server-side validation fails AjaxContinuation output reads:
					{ "success":false,
								"errors":[{
											"category":null,
											"field":"UserName",
											"message":"Required Field"
											},
											{
											"category":null,
											"field":"Password",
											"message":"Required Field"
											}
											]
					}
					*/
					if(response.success == false){
						for (var i=0; i<response.errors.length; i++)
							$("#"+response.errors[i].field).addClass("error");
					} 
				},
				error:function(x,e){
					alert("error : " + x.status + " - " + e);
				}
			});
		});
	});
</script>

<form id="logonForm" action="log-on" method="post">
 <label>Username</label>
 <input type="text" id="UserName" name="UserName" />
 <label>Password</label>
 <input type="password" id="Password" name="Password" />
 <input id="btnSubmit" type="submit" value="go"/>
</form>

PostHandler.cs

public class PostHandler
    {
        public FubuMVC.Core.Ajax.AjaxContinuation Execute(LogOnInputModel input)
        {
            return new FubuMVC.Core.Ajax.AjaxContinuation
            {
                Success = true
            };
        }
    }