Changing the name of output SWF in Flex Builder on Mac
If you’d rather output a swf with a different name as your main application class, you can set a custom compiler flag in your project settings*:
-o “/Volumes/Macintosh HD/path/to/myproject/newname.swf”
*Note: if your file path has spaces in it, wrap it in double quotes.
Source: airtightinteractive.com