From the gesture settings, there is no way to get the 4 finger swipe back.
Which is why I gave the tip about Better Touch Tool. Works like a charm for me. Allows you to set up the gestures just like you want them, old-school SL style if you like.
I cant thank you enough for letting me know about Better Touch Tool. I was going so mad because i couldn't use the 4 finger swipe to bring up the application switcher, i use it all the time.