On my php sites you can change the apparent image source using htaccess. Is there anyway to do this on asp sites? Images would actually be from site A, but if you peak at the source it would say it's from site B.

If you control the web server, I've heard there are .htaccess and mod_rewrite add-ons available for IIS

In IIS you can use any local or network drive as a web-root or subfolders, so with this way you should be able to assign a completely different folder as a sub-web for your main page, making it appear like the folder is physically under your root but actually on a completely different location.