- Invoke Quicksilver (probably by pressing Control-Space)
- Press Command-, to open its preferences
- Go to Preferences » Application, and make sure 'Enable advanced features' is checked
- Go to Catalog » Quicksilver and make sure 'Proxy objects' is checked
- Go to Triggers and click the plus sign to add a new trigger and select Hotkey
- Start typing Current Selection, and when the item pops up, press Tab
- Start typing Move to... and then press Tab
- In the last box, press Command-X clear the field. It must be completely empty for this to work -- no text, nothing
- Click Save
- Click the 'i' at the bottom right of the screen to show the trigger options
- Under hot key, choose your preferred key command; I've chosen Shift-Command-X (see note below)
Note: Quicksilver has a Scope function for the triggers which can limit the trigger to one app. In this case, the scope should be limited to the Finder. The Scope function, however, is broken under Leopard. If you're using an older version of OS X, you might be able to limit the trigger to the Finder and just use Command-X as the hotkey. Setting it to Command-X under Leopard, however, will break the Cut command in all apps.

