how can I get the onkeydown event from tinymce field?

hello everybody,
what must i do to get e. g. the "onkeydown" event from tinymce field?
take a look at the code i tried, but does'nt work
greetings from cologne
manfred

<?php echo elgg_view("input/longtext", array(
  "internalname" => "tinymce_field",
  "value" => $text,
  "onKeyDown" =>  "textbeamer('#fromfield,'#tofield')",
  "onKeyUp" => "textbeamer('#fromfield,'#tofield')"
  ));
  ?>