Cant get ScriptResource.axd / WebResource.axd anonymous access working?

Question

I'm pulling my hair out and going around in circles it seems at the moment trying to solve this. I have a windows authenticated site, with a particular folder which I don't want to authenticate against. It has a script manager on the page with an update panel, but whenever I load the page I am getting prompted to log in. If I look at Fiddler, I am getting 401 errors for where they are trying to load.

So far I have tried the following solutions:

Added a blank ScriptResource.axd and WebResource.axd file to the root.

Added allowed paths to the web.config

<location path="ScriptResource.axd">
    <system.web>
      <authorization>
        <allow users="?"/>
      </authorization>
    </system.web>
  </location>
  <location path="WebResource.axd">
    <system.web>
      <authorization>
        <allow users="?"/>
      </authorization>
    </system.web>
  </location>

Added the following handlers to the web.config

 <system.webServer>

    <handlers>
      <add name="ScriptResource" preCondition="integratedMode" verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>

    </handlers>
  </system.webServer>

But nothing seems to work and I'm running out of links on Google?

Any help would be much appreciated.