Custom Rewrite Provider for Response body filtering ?

Hi,

   We are working on a Reverse Proxy cum URL Rewrite solution. Different customers access their portal through our parent domain, using a URL based approach. For example

For customer1 : URL -> ourportal.com/customer1

For customer2 : URL -> ourportal.com/customer2

 Our servers are Windows Server 2008 based. We use using

- URL Rewrite 2.0

- Application Request Routing 3.0

- External Cache 1.1    

We are able to configure Inbound Rules and route the https requests to the relevant web servers. Unfortunately the images and styles ( hence some controls also) do not appear properly. So we are updating the references to images and CSS in https response.

   Since there are many different matches and conditions, the configuration is complex. The C# code based approach looks like a better one. We already looked at :

http://www.iis.net/learn/extensions/url-rewrite-module/developing-a-custom-rewrite-provider-for-url-rewrite-module

This is very specific to InBound rules and processing. How do we do a similar filtering on Response body through C# ?

Aditya