MEX file debugging with Xcode 4.6

Hi, I have a mex file that I'd like to debug using Xcode 4.6.3 on Mac OS X 10.8. I found this page http://www.mathworks.com/matlabcentral/answers/97509 which tells how to debug with Xcode 4.3, 4.4 or 4.5, but this seems to be out of date since the ~/Library/Developer/Xcode folder referenced in step 1 does not exist on my system. Has anyone figured out how to do this for newer versions of Xcode? Thanks for any input!