No, you won't be able to do it with a webbrowser control, but you can create a proxy server running on localhost that can apply filters you need.
In fact there is a number of ready solutions available on the web - Privoxy, Proxomitron, AdMuncher, etc.

To create your own proxy filter you would need System.Net and System.Net.Sockets namespaces and HttpWebrequest and HttpListener classes.