Hi Kenneth,
Well, short answer is - you can't do that. I assume you want after all to execute application markup back on client when you receive it from server side, that is impossible. MXML compiler is actually translator-compiler, works exactly same way as we (at Skitsanos) did with BLOC some time ago, taking application markup, translates it into ActionScript and only then compiles into byte code.
Only thing you can do is to create sort of interpreter, where you will run quite a long loop to get a structure of all your objects and their styles and store it with xml representation, but it wont keep any behavior like event handlers and so on. So this xml you can pass to your web server and get it back. You will need to solve only this "little" interpretation issue...
Cheers,
Evi.
--
Evgenios Skitsanos
blog:
http://blog.skitsanos.com/twitter:
http://twitter.com/skitsanos