HTMLLoader - Embed local .html in remote .html using iframe.sandboxRoot and iframe.documentRoot ?

Question

Hi! This already took me hours of research and testing but I might misunderstand this part of the Adobe AIR documentation:
http://help.adobe.com/en_US/AIR/1.5/devappshtml/WS5b3ccc516d4fbf351e63e3d118666ade46-7f08. html#WS5b3ccc516d4fbf351e63e3d118666ade46-7f07
The problem:
Huge fancy HTML5 elearning project with loads of assets but users with superslow (GPRS like) internet connection.
Solution (idea):
Provide USB-sticks with most of the static course data (all SCOs) and somehow redirect server requests to this files.
More concrete concept:
1. On this USB stick we also provide a Adobe AIR "wrapper" app with captive runtime (since users are no admins) which starts a StageWebView or HTMLLoader instance to access the online server. No problem.
2. This HTML wrapper also submits the local path to our data directory on the USB stick. Should also work fine.
3. The server then writes different <iframes> for this specific wrapper app and within the Adobe AIR WebKit runtime all requests from (example) http://mydomain.com/data/ would be redirected file:///path/on/usbstick/to/data/ .
Well, I thought this <iframe> would do the trick:
<iframe
     src="http://mydomain.com/data/content1.html"
     sandboxRoot="file:///path/on/usbstick/to/data/"
     documentRoot="file:///path/on/usbstick/to/data/"
     >
</iframe>
But unfortunately it doesn't. Of course I tried already almost all possible settings for src, sandboxRoot and documentRoot but it still didn't work:
var innerHTML = "";
var possibleSrc = ["content1.html", "http://mydomain.com/data/content1.html", "file:///path/on/usbstick/to/data/content1.html" ];
var possibleSandboxRoot = [ "http://mydomain.com/data/", "file:///path/on/usbstick/to/data/", "app:/data/" ];
var possibleDocumentRoot = [ "http://mydomain.com/data/", "file:///path/on/usbstick/to/data/", "app:/data/"];
for ( var i = 0; i < possibleSrc.length; i++ ) {
     for ( var ii = 0; ii < possibleSandboxRoot.length; ii++ ) {
          for ( var iii = 0; iii < possibleDocumentRoot.length; iii++ ) {
               var src = possibleSrc[ i ];
               var sandboxRoot = possibleSandboxRoot[ ii ];
               var documentRoot = possibleDocumentRoot[ iii ];
               innerHTML += '<iframe class="content" src="' + src + '" sandboxRoot="' + sandboxRoot + '" documentRoot="' + documentRoot + '" allowcrossDomainxhr="true"></iframe>';
So now my questions:
Is it possible?
Can I create with AIR an HTML wrapper which provides access to the files on the USB stick?
Is there some other technique out there which can do what I need?
I would really love to get at least some hints...

Answer 1

Just to give you a hint if you're researching this topic: Seems like only Firefox portable has the ability to rewrite security rules. So you might look in this direction.