Don't know if it will work with a USB numpad, but there's a freeware program called Sharpkeys that I use on my laptop to make the Capslock key into a Windows key. It might do what you're looking for.

SAN ANTONIO – A third arrest has been made in a crime ring involving a group of suspects accused of stealing nearly one dozen vehicles by reprogramming car keys. Miguel Gonzalez, 20, was arrested ...