Scripting question.

I use Fireworks MX (and Dreamweaver MX), though not so much now Geocities is closed.

I have a task to perform and I see batch scripting as an option, but haven't seen much by way of tutorials.

I want to take the contents of two different .bmp files and export a third .bmp file that displays the two original images side-by-side.

Then I want to automate that process for two sets of, say, 1000 sequentially titled files (aa0001.bmp, aa0002.bmp, etc)

How would I go about this? Is there a better tool for the task that someone can recommend?

Thanks in advance.