Character count and limit

I like very much the new CKEditor, but I'm quite desperate : I think that I have read all the topics and all the tickets about counting characters and setting a maxlength to a CKEditor textarea... I still have not been able to make any of the solutions work.
I asked the same question here http://cksource.com/forums/viewtopic.php?f=11&t=15716 but I think that I should have asked it in this forum...

My test programm is here http://www.lgv.on-web.fr/valinfotest/testcke.php

I'm totally a newbie in Javascript, so, please, as I really need a characters counter and limiter... I really need help...