Hello, there, my friend,
Unfortunately the plugin is tied to the implementation of Apache and needs the .htaccess file to function. What needs to be added to the .htaccess file is some special rewrite rules which will funnel the requests for images to the adaptive-images-script.php file. With the .htaccess file the plugin can write these directives itself:
# BEGIN Adaptive Images
#=======================
<IfModule mod_rewrite.c>
RewriteEngine On
# Watched directories
RewriteCond %{REQUEST_URI} /wp-content/uploads [OR]
RewriteCond %{REQUEST_URI} /wp-content/themes
# Redirect images through the adaptive images script
RewriteRule \.(?:jpg|jpeg|png|gif)$ /wp-content-takis/plugins/adaptive-images/adaptive-images-script.php [L]
</IfModule>
# END Adaptive Images
The reason we have chosen to support this is because Apache (and therefore the .htaccess files) are the most commonly used setup, since the vast majority of web hosting environments out there use them. Also, some people have manually written the necessary code to add the respective directives for NginX.
It would be great if you, or anybody else, could do the same for IIS, but it is totally out of our general scope to provide this kind of automation (and debugging) for it. I would be glad to help in any way possible in order to help you with that. So sorry, I cannot do much more!
Cheers,
Takis