Not a good idea, because Filezilla has no applescript support. I've always been surprised that Cyberduck doesn't either. But see:
http://discussions.apple.com/thread/2588937?start=0&tstart=0
.... on which there are good directions; curl in shell, or (at the end of the page) URL Access Scripting, which is a scripting addition that should be installed on your Mac. URL Access Scripting example:
tell application "URL Access Scripting"
upload filepathtoUpload to "ftp://username:password@domain.com/SOME/PATH/filename.jpg" replacing yes without binhexing
end tell