From the Steinberg web site:

In conjunction with Steinberg, (:wizoo:) the well known sound designer company, programmed an indispensable utility for creating your own sets easily. Just type in the name of the created script file without the ending *.txt as a program into the VST Instrument rack and groove! The Drum-kit Editor is freeware. That means you are allowed to download it at no charge, to use and to pass it on. Please note that we are not able offer technical support, and because it's freeware, we cannot take any responsibility for any defects or side-effects caused by this software. You agree to these conditions by clicking the download links.