Are non-unibody MacBook Pros capable of Lion's 3 and 4 finger multi-touch gestures?
No - that era of hardware is a solid-state trackpad, not a multitouch trackpad and can only track one motion. Although it can guess fairly well if it's one finger or two that is moving in two dimensions (left-right and up-down), but that's all the hardware can tell. 

Put another way, yours tracks the center of all touch points combined, not several touches individually at the same time with their own motion.