initially, i couldn't quite figure out how to do that, but finally found the answer here http://kinkless.com/node/107

- Open QS Preferences.
- Select Triggers on left side.
- Click "+" for new trigger.
- Type "KGTD" to navigate to the script.
- Hit Tab.
- Hit Save.

although i had to manually navigate to the script to select it -- you can find the script in this folder: ~/Library/Application Support/Quicksilver/Actions/ (you can type ~ in qs and it puts you to the user folder and then use the arrow keys to navigate the folders.)

i set it up to be apple-shift-k as my hotkey. so no matter what i'm doing, i hit that, type in something i want to remember, and it will end up in my inbox in my kgtd document.
good luck