Using RequestFiltering feature, other way around

I came across a simple request from customer wherein they wanted to use 'request filtering' feature in IIS by setting 'Allow unlisted file name extensions' to unchecked. Simple request but it created mess to our product and it started showing up HTTP errors. By adding few extensions (for e.g. isapi_redirect.dll) it started working by opening few webpages but failed later. I also tried to use 'Allow URL' feature by adding few URLs but since our URLs are generated dynamically (struts mapping) we can't add each and every URL under this option.
All the options were searched but at the end we could locate 'URL rewrite' which gives handy options to allow or deny based on RegEx or WildCards.
More description can be found in this below link:
http://stackoverflow.com/questions/24034498/iis-request-filtering-allow-url