Do you mean the actual area that displays the content? The internal <textarea> element is already rendered with an ID, which is preserved after CKEditor initializes in the client. So, I suppose you want to access the actual area where the text is displayed with all the formatting, etc. Right? If that's the case, we would have to modify the CKEditor code to apply an ID to it, but I'm not sure that would really help, since all that area is inside an iframe, and often times it's not possible to access anything inside an iframe from the outside/host page. This area is actually the 'body' element of the iframe, so you might want to try first to access it by specifying this body element inside the iframe, or you can try to access it by specifying the 'cke_editable' CSS class as a selector. If it's not possible to access elements other than by ID, from the testing scripts, then we can try adding an ID and see if it works that way.

I have found a way to force webdriver to switch to the iframe then use Javascript Executor to edit the inner html so that I can enter and submit content. For now I can use this workaround.