Now we can use the SWC files created for Flex applications in Flash.
Just we need to add the SWC to Flash compiler. Follow the steps to use Flex SWC files in Flash development.

1. Open new File Flash CS4.
2. Select File > Publish Settings or Press Ctrl + Shift + F12, Publish Settings window will Popup.
3. Click on Settings… and Select Library path

4. Click on Plus Symbol to add SWC path or File.

5. Copy and Paste the Flex SWC files Path.

For example:C:\Program Files\Adobe\Adobe Flash Builder Beta 2\sdks\4.0.0\frameworks\libs

Thats it now we can compile SWC files created for Flex Applications.