On OS X privileged operations are done through AuthorizationExecuteWithPrivileges() around which Apple published two recommendations:
The old MoreAuth using setuid helper tools.
The current BetterAuthorizationSample littering the system with launchd files.
I don't know any applications using the latter...
I've used it, and it's a pain to implement. FWIW, I know that BBEdit and PGP Desktop use it.