You can create a custom component and override functions (but not all functions).
I'm not sure if that information will help you, because I am not sure what you are trying to do in your code.
Here my problem in detail.
I have a Flex Project in Eclipse.
I connected the Flex Builder Plug-In to this Project, so I can use all the libraries from the Flex Builder itself.
Know I have the problem, that after 2 minutes without any feedback from my server the application automaticly starty an time out error message.
I found out that this error message was set from the file MessageResonder.as which is a part from the Flex Builder.
I now changed the ActionScript file but just changing the ActionScript file is useless, because my programm is connected with compiled sdk from the Flex Builder.
Now is my Question, how can Ii add my changed ActionScript file to the compiled sdk? Or how do I compile the whole library again?
The only thing I could find was attempting to add some sort of listener that would be able to catch the timeout, which would be outside of the function used to call the web service or server call.