Accessing stage of externally loaded swf

I am loading an SWF created in Flash CS4, using the 3d translation tool.
The SWF is being loaded into an application being build in as3 in flex builder 3.
I can manage to load the movie however the stage has disappeared. All of the objects that exceed the boundaries of the (banner) remain visible instead of being cropped by the stage. I attempted to mask the swf before publishing which did not work, and I attempted to programmatically assign a mask once it was imported which also did not work. None of these options threw errors, in most cases they either had no effect whatsoever or the movie simply disappeared. I’ve read numerous posts on this and the answers always seem to be vague. Does anyone know how to account for this distortion?
Based on my research I need to access the stage properties of the SWF being loaded, but am unsure how to go about it.

Do I need to compile the movie, export a swc and add it to the build path for the project?
Do I HAVE to use a document class for the SWF I want to load in order to access it?
Do I need to add anything else to the source or build path for the project in Flex Builder? (i.e. assign CS4 classpath to flex)