// Initialize API
HpdApi api = HpdApi.GetInstance();
api.Init();

// Open a project and a workdesk.
Project project = api.OpenProject(@"c:\Projects\MyProject.hxproj");
					
Variant variant = project.GetVariants().FirstOrDefault();
Designer designer = variant.GetWorkdesks().FirstOrDefault(d => d.Name == "Workdesk_1");
designer.Open(false, false);

IOccConnector connector = designer.GetAllOccurrences().OfType<IOccConnector>().FirstOrDefault(c => c.Name == "cn_00001");
IPinBase pin = (connector as IRPAddPin).RapidPartAddPin();

// Save changes and close documents.
designer.Save();

designer.Close();
project.Close();