It is real simple for the Countdown just change line 9 to:
var content="<!--System:CountDown-->";
Note: I used double quotes ("), if you keep the default single quotes (') it will cause and error.
Make sure that the script is in your layout.htm page. Do not make it a separte file. I am not sure it will work correctly other wise. Like so: <script type="text/javascript" language="javascript">
//the ticker code here
</script>
As for the <!-- System:OnlineOnly --> I am not sure what that does if it is like the <!-- System:Online --> It will be much more complex to pull out the data for use in that code. If you could let me know what it does I may be able to rewrite the code for you to do it.