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Download the Xcode Template and put it in
(~)/Library/Application Support/Apple/Developer Tools/Project Templates/
Create the folder if needed.
In Xcode, you need to create a Source Tree that points to your Quicksilver Frameworks directory. Go to the Preferences > Source Trees section, add a new entry with the setting name as QSFrameworks. Set the path for this item to /Applications/Quicksilver.app/Contents/Frameworks/ or the equivalent.
Plugins are loaded from any of the standard locations as well as from the current directory, so as long as you launch from Xcode it should work.