Project: SuperCollider UGen templates for Xcode
Download the zip file, extract and drop the entire enclosing "SuperCollider UGens" directory into:
/Developer/Library/Xcode/Project Templates/Application Plug-in
You will also need to have downloaded the current SuperCollider source tree for its header files and the plugin interface. Either install it in the default location, at /Applications/SuperCollider, or, within the Xcode "Groups & Files" pane of your UGen project, change the path of the "SuperCollider" group to point to the SC source tree.
More info in the README.