To append entry to log component which would append entry processor is sending following stanza with proper values set:

<iq type="set" id="auditlog-1">
  <append xmlns="http://tigase.org/protocol/auditlog">
    <entry>
      <whenOccurred>2015-01-15T14:54:04Z</whenOccurred>
      <srcAddress>user1@example.com</srcAddress>
      <dstAddress>user2@example.com</dstAddress>
      ...
    </entry>
    ...
  </append>
</iq>

This would notify receiver to append (as append is name of action element) entry or entries which are described by inner elements of action element.