<FORM name="controles">
<TEXTAREA name="codigovrml" . . .></TEXTAREA>
<INPUT  type="button" name="update" value="Actualizar VRML" onclick="updateVRML()">
</FORM>

<EMBED src="eai-vrml.wrl" align="baseline" border="0" width="300" height="300" name="vrml">

<SCRIPT>
function updateVRML() {
  document.vrml.replaceWorld(document.vrml.createVrmlFromString(document.controles.codigovrml.value));
}
</SCRIPT>