How do I make magic trackpad scroll one way but mouse the other way?

I just added a magic trackpad and love it but I'm SO used to my trackpad scrolling one way and mouse the other. this is an easy transition on my mac mini when using a mouse vs my macbook pro but now that I'm using a mouse AND a trackpad, it's hard to work both.

biggest thing would be if I could change trackpad swipe left/right to go in the opposite direction it is without affecting the scrolling of the mouse. is this possible?