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.