The short of it is as follows:
- Download q2kyb02us13.exe. Then extract and install first by executing C:\SWTOOLS\DRIVERS\KYB\v2kyb03us17\Setup.exe
- Download q5kyb07us13.exe. Then extract and install second by executing C:\SWTOOLS\DRIVERS\KYB\v5kyb04us17\vista\x64\setup.exe
I posted this because I tried downloading executing the bigger file first (and only), and then rebooting (several times), and it never actually worked. Normally IBM installs are fashioned as such - "install the bigger installation if you want everything, or install the smaller installation if you want the barebones driver". This wasn't the case. It's definitely a 2-part install. If you do it any other way, you will not get it to work like a standard ThinkPad keypad (the scroll will be missing, the mouse properties will be bare-bones, and you will be very annoyed as I was).
I learned this after about 2 hours of fiddling.
Hope this helps someone!