That's done by the software, not PB-Pro. It needs PB-Pro because a standard powerbase (old type) cannot be controlled by a computer, it can only report data to the computer. PB-Pro allows the computer a lot of control, and so SSDC can record a lap and play it back. The new powerbase is capable of this level of control as well, it's just a matter of the new SSDC coming out and getting the new Aux cable to connect it to the PC.
When I speak of "pace cars" I mean constant throttle ones. I've more or less given up on recorded lap pace cars, at least for my current layout, because it takes too much tweaking for the car to reliably lap without coming off, and by that time, it's no kind of competition. I have what some may consider too many R1 turns (3!), but even on a layout with nothing tighter than R2, a recorded lap will never be a real match for a human driver. Andrew has plans for fancier things in the new version for the new PB. Time will tell if it's better than what we have now. I still doubt it will be a match for a human driver unless the car is faster/better than the one the human is driving, in which case, might as well KISS and do what I originally suggested for constant throttle cars.
Of course, this is completely off topic, and belongs in an SSDC thread of some kind. Anyone have any requests for future videos?