public string PortalProjectCustomDefaultToolbox {get; set;}

{
  // access the current options
  var def_home = ApplicationOptions.GeneralOptions.PortalProjectCustomHomeFolder;
  var def_gdb = ApplicationOptions.GeneralOptions.PortalProjectCustomDefaultGeodatabase;
  var def_tbx = ApplicationOptions.GeneralOptions.PortalProjectCustomDefaultToolbox;
  var deleteOnClose = ApplicationOptions.GeneralOptions.PortalProjectDeleteLocalCopyOnClose;
  var def_location = ApplicationOptions.GeneralOptions.PortalProjectDownloadLocation;

  // set the options
  ApplicationOptions.GeneralOptions.PortalProjectCustomHomeFolder = @"E:\data";
  ApplicationOptions.GeneralOptions.PortalProjectCustomDefaultGeodatabase = @"E:\data\usa.gdb";
  ApplicationOptions.GeneralOptions.PortalProjectCustomDefaultToolbox = @"E:\data\usa.tbx";
  ApplicationOptions.GeneralOptions.PortalProjectDeleteLocalCopyOnClose = false;
  ApplicationOptions.GeneralOptions.PortalProjectDownloadLocation = @"E:\data";
}