HRESULT _result=S_OK;
IConnectionPointContainer* _connection = NULL;
IConnectionPoint* _point = NULL;
DWORD _cookie;
bool _connected=false;

_result = OBJECT_WITH_EVENTS->QueryInterface(IID_IConnectionPointContainer, (void**)&_connection);

if(SUCCEEDED(_result))
{
    //DIID_IEvents - event interface;
    _result = _connection->FindConnectionPoint(DIID_IEvents, &_point); 
    
    if (SUCCEEDED(_result))
    {
        _result = _point->Advise(POINTER_TO_IUNKNOWN_INTERFACE_OF_EVENT_HANDLER_OBJECT, &_cookie);

        if(SUCCEEDED(_result))
        {
            //Connected...
            _connected=true;
        };

        _point->Release();
    }
    _point->Release();
}

//...

if(_connected)
   _point->Unadvise();

class YOUR_EVENT_HANDLER : public IDispEventImpl / IDispEventSimpleImpl<...>
{
 //...

 BEGIN_SINK_MAP
    SINK_ENTRY/SINK_ENTRY_EX/SINK_ENTRY_INFO
 END_SINK_MAP
};