Can you program in flash? I mean, I know you can, but do you know how to it.
Perhaps you can program your flash movie that checks the url of the page and give the correct situation.

If it was my site, I would make different skins. Be aware that I don't use my css files in the skin folders, but in the folder above and use the style.config to tell the system where the css files are.

Stef

... however putting this logic into the client site code strikes me as wrong...

Perhaps, but from all the years that I'm working as a web developer, and working with different cms systems, I know you have to work around sometimes. If you have full control of the site and you know how to work with flash, I would not mind doing it that way. But, I would put everyting in an xml file (page -> image(s)) and let the flash movie read the xml file. That way, if you have new pages, you just need to change the xml and not the flash .

... also ceating different skins just because I have one image difference feels heavy handed...

Well, I'm working that way for my sites. Cause I don't use automatically width's of the colomns, but hardcoded (specially made for SEO), so I have different skins, just for having 1 colomn layout or 3 colomn layout. But all my css files are NOT in the skin folder, but the folder above and that is working just great with the style.config.