WCF Service

I am wondering if there is anyway to retrieve all worklist items from the WCF service. Currently all I am getting back when writing a sample app are those worklist items assigned to me. Previously we had used code like below to impersonate a user based on login, but I can't seem to figure out a way to do the same through the service. Any help would be appreciated.

ConnectionSetup K2ConSetup = new ConnectionSetup();

                    K2ConSetup.ConnectionParameters.Add(ConnectionSetup.ParamKeys.Host, ConfigurationManager.AppSettings["K2Server"]);

                    K2ConSetup.ConnectionParameters.Add(ConnectionSetup.ParamKeys.TimeOut, ConfigurationManager.AppSettings["K2ConnTimeOut"]);

                    //Open a connection to the K2[blackpearl] server

                    K2Con.Open(K2ConSetup);

                    K2Con.ImpersonateUser(login);

                    Worklist K2WorkList = K2Con.OpenWorklist("ASP");

                    K2Con.RevertUser();