One way to get what you want would be to use the hard button as a right click instead of a left click. Sidetrack lets you do this, but you lose the two-finger taps. (Corner taps instead.)

I'm not sure how the new MBP trackpad will handle the multiple buttons. I've never used any of the multitouch pads, but I did use the Fingerworks Touchstream keyboard, on which the multitouch tech is based. On that keyboard, you could easily do drags with any of the button gestures. I think the default was index and middle finger was left-click, index, middle, and ring was right-click, and index, middle, and thumb was middle-click, any of which could be dragged.

The implementation on the trackpad is probably more limited, but I haven't found any details to confirm that.