Even though the API has been open since Mac OS X Leopard, there\'s surprisingly, and unfortunately, very little documentation on how to correctly use SMJobBless()
Itai have you looked at the SMJobBless sample code from WWDC 2010? It includes a helper tool and app to bless it.
https://developer.apple.com/library/mac/#samplecode/SMJobBless/Listings/ReadMe_txt.html#//apple_ref/doc/uid/DTS40010071-ReadMe_txt-DontLinkElementID_3
Its README file says:
This sample as it stands does not actually run the helper tool. The following samples show how to [sic] a launchd job and set up interprocess communication: