Does anyone know how to pass a List<t> to a WCF Service

I have a WCF service that accepts a List<participants> as a parameter and I need to call it from the client ie javascript.  Can this be compeleted?

I'm looking to do something like.
var svc = new EMService();
                var valParti = $('#ddlParticipant').val();
                var list = new List<Participant>();
                var part = new Participant();
                list.Add(part);
                svc.SendMessageAll(list, onSuccess, null, null);