This example shows an object that supports IPropertyNotifySink as an outgoing interface:
class ATL_NO_VTABLE CConnect1 :
   public CComObjectRootEx<CComSingleThreadModel>,
   public CComCoClass<CConnect1, &CLSID_Connect1>,
   public IConnectionPointContainerImpl<CConnect1>,
   public IConnectionPointImpl<CConnect1, &IID_IPropertyNotifySink>,
   public IConnect1
{
public:
   CConnect1()
   {
   }
DECLARE_REGISTRY_RESOURCEID(IDR_CONNECT1)
BEGIN_COM_MAP(CConnect1)
   COM_INTERFACE_ENTRY(IConnect1)
   COM_INTERFACE_ENTRY(IConnectionPointContainer)
END_COM_MAP()
BEGIN_CONNECTION_POINT_MAP(CConnect1)
   CONNECTION_POINT_ENTRY(IID_IPropertyNotifySink)
END_CONNECTION_POINT_MAP()
   DECLARE_PROTECT_FINAL_CONSTRUCT()
   HRESULT FinalConstruct()
   {
      return S_OK;
   }
   void FinalRelease()
   {
   }
public:
};
When specifying IPropertyNotifySink as an outgoing interface, you can use class IPropertyNotifySinkCP instead of IConnectionPointImpl. For example:
class ATL_NO_VTABLE CConnect2 :
   public CComObjectRootEx<CComSingleThreadModel>,
   public CComCoClass<CConnect2, &CLSID_Connect2>,
   public IConnectionPointContainerImpl<CConnect2>,
   public IPropertyNotifySinkCP<CConnect2>