We recently needed to change, and move, the default Interactive Report (IR) AJAX "Loading" image (spinning wheel): After some investigation they're several things you can do depending on your requirements. A demo application is available here.
Before we go over the solution it's important to review where the image is located and how it gets toggled on and off. The image is stored in a span region which is hidden by default. The code looks like this:
If you want to manually make it visible you can run the following code:
First Let's build a IR page with the emp table:
select * from emp connect by level
The easiest option is if all you need to do is change the image:$('#apexir_LOADER img').src="#IMAGE_PREFIX#processing3.gif";
The new image, processing3.gif, is part of APEX as well. You can reference your own images if you'd like.
In Part 2 I'll go over changing the actual function that shows and hides the loading image. This will give you complete control of the loading message.