I don't use the trackpad at all so I don't have that problem. :)
You could try playing around with the settings in /sys/devices/platform/i8042/serio1/. The file "sensitivity" or "rate" might be what you're looking for.
Sadly, I've tried it all. It seems that the 80Hz cap is enforced by the kernel PS/2 driver, for whatever reason, and is shared between the touchpad and the TrackPoint since they are on the same bus. I can only imagine drivers under Windows employ some proprietary trickery to get around that limitation.