Step 4: Go Criteria Crazy

You can set your Find default to include as many extra criteria as you wish; to find out how to change the keys in the plist file, simply create and save a Smart Folder. Press Command-F, and select the criteria you want for your new default; type something (it doesn't matter what) into one of the search fields to activate the Save button. Press the Save button, and save the Smart Folder to your desktop. Drag the Smart Folder icon into TextEdit - the Smart Folder will open just like default_smart.plist did, revealing all of the FXSliceKind keys for you to cut and paste into the default_smart.plist file.

Paste these keys into your plist to make them part of the default search criteria.