Fyi.. I searched Apple.SE and didn't found an answer, so I am posting here.
Currently I open Quicksilver by Ctrl + Shift + spacebar. And my Spotlight preference is Cmd + spacebar.
Most of the time I use Quicksilver, I would like to change this. I know how to change this for spotlight, but not sure for QS.
Now I am able to see the preferences screen with some menu's and here is the screenshot. Am I running very old build/ version ?