BleepingComputer Review:

Kensington TrackballWorks allows you to customize your TrackBall's buttons and change its pointer speed and acceleration. This is the MacOS version of this software.

Product Description from Kensington:

Kensington TrackballWorks™ is software that allows you to customize the functions of each of the buttons found on your trackball. The result is a more productive and truly personalized computing experience. Now you can set your preferred functions or keyboard shortcuts for each trackball button or combination of buttons, adjust the pointer speed and acceleration and do so much more. Best of all, by allowing you to personalize your trackball experience, TrackballWorks™ makes your trackball work the way you do.