[CMake] xcodeproj internal reference lottery

[hauns at mac.com]

i am using cmake 2.8.0 on mac os x 10.6.2 with xcode 3.2.1 for generating .xcodeproj files for a large cross platform project. 

internally, .xcodeproj package files neatly distinguish project from user data information (such as debug settings) in separate files: project.pbxproj and user.pbxuser. in there, file references are tracked by hex ids: 

  104043E30104043E30104043 /* main.cpp */ 

now it happens, that each time i sync to head of the repository (with typically only a handful files changed) and recreate the project, cmake selects a complete new set of hex ids for its project.pbxproj file. as a result, user.pbxuser (while it does not get overwritten by cmake) is rendered no longer useful and is subsequently reset by xcode to default. 

is there a way to preserve those hex ids (or my debug setting for that matter)? maybe cmake could be configured with a "seed hex ref" from which all others are derived in a consistent manner. 
[on win_vx90 this works - maybe refs are stored by path rather than id] 

thank you.