Add element to image tag output

I would like to add class="entryImage" to the output of the images when I add them.  Where and what can I add to the RTE structure to make this happen?

Put another way: when I add an image, the outputted code is this:

<img src="http://www.imageurl.com" border="">

I would like it to look like this:

<img class="entryImage" src="http://www.imageurl.com" border="">

Help?

Thanks boRg -

Do you know which one is the page that processes the form input?

Ah - I see. I looked at the code on popupimage.asp and got the impression that RTE made some sort of alteration to the code, but I see now that that is just for the pop-up window.

So I guess there's two things, I could do:

1. write some "replace" code that takes "<img" and turns it into "<img class="entryImage"

or

2. I didn't think of this before, but I could just switch to HTML veiw in RTE and type in the code myself before I submit the form.

Thanks boRg