This document assumes that you have already set up Ogre on your system, and you are able to build the Ogre Tutorial framework using XCode. The libraries in these instructions are cegui-0.8 built with XCode.
If you still need to install Ogre on the Mac see my instructions for installing Ogre and setting up Xcode.
In the User-Defined section add the variable CEGUI_HOME with the value /PATH/TO/cegui.
In the Search-Path section add ${CEGUI_HOME}/include/cegui-0 to Header Search Paths.
Also in the Search-Path section add ${CEGUI_HOME}/lib to Library Search Paths.
In the Linking section add -lCEGUIBase-0 and -lCEGUIOgreRenderer-0 to Other Linker Flags.
Ogre's Basic Tutorial 7 introduces Ogre with CEGUI. Make sure you follow the instructions specific to "CEGUI 0.8.x".