You can't. An .SWF file is to an .FLA file as a .DLL is to a .CS file. An SWF file is, essentially, a compiled version of the Flash movie and it can not be edited directly. You will need the source file (.FLA) to make these types of changes.
================================================== =========
Read this if you want to know how to get a correct reply for your question:
http://www.catb.org/~esr/faqs/smart-questions.html
================================================== =========
.: Wrox Technical Editor :.
Wrox Books 24 x 7
================================================== =========