def setup_event_request(self, issuer_id, event_type, params=None, change_by=None ):
        """ Perform the necessary magic when creating a pending confirmation
        event (i.e. create a changelog entry with the event).

        @type issuer_id: int
        @param issuer_id: The C{entity_id} of the event creator/inviter

        @type event_type: Constants._ChangeTypeCode
        @param event_type: The changelog type that should be used to store this event.

        @type params: obj
        @param params: An object containing other arbitrary information that
                       relates to the L{event_type}.

        @rtype: str
        @return: The confirmation key, or ID, of the newly created event.
        """
        return self.db.log_pending_change(issuer_id, event_type, None,
                                          change_params=params,
                                          # From CIS, we don't have the
                                          # change_by parameter set up, should
                                          # set this in the request
                                          change_by=change_by)