I found the solution For packages containing
.swf files here :
To improve iteration time, the gfximport commandlet, run from your Unreal Engine 3 executable (e.g UDKLift.exe) allows for content importing and reimporting without loading Unreal Editor. The commandlet assumes that content has been arranged in the manner described above.
In order to import a file, you must run gfximport commandlet while specifying relative paths to all of the .SWF files within the GameDir\Flash directory that you wish to import separated by spaces.
UDKLift.exe gfximport [path_1] [path_2] [path_3]
In order to re-import files that are already imported into UE3, simply run the commandlet with no arguments.
The commandlet will reimport all the SwfMovies for which the .SWF file on disk is newer than the one imported.
Suppose you want to import these files.
You would execute the following command:
UDKLift.exe gfximport UI/MainMenu.swf UI/Resources.swf
They will be imported into the UI package as SwfMovie'UI.MainMenu' and SwfMovie'UI.Resources'. The package will be saved as GameDir\Content\GFx\UI.upk.