I usually just check these whenever they try to add something:
1. Game page source (check flashvars)
2. Gameversion.asp (check if something changed)
3. Loader.swf (decompile and check, usually they add another variable)
4. Game.swf (decompile and check the login function)
5. Fiddler (check the requests and see the headers and cookies)
Once you found the changes, apply it to as3>publish>change the old file in C#>build>and see if it works.
I can provide some help but I won't touch anything, not to be rude but so you can learn it by yourself