$docprops =  $doc->CustomDocumentProperties();
 unless (defined ($doc->CustomDocumentProperties($property)))
 {
    $docprops->Invoke('Add', {
                               Name => $property,
                               LinkToContent => 0,
                               Type => 4, #msoPropertyTypeString 
                               #strictures to work around still
                               Value  => $value,
                              });
  }
  $doc->CustomDocumentProperties($property)->{Value} = $value;