qt mac osx 10.8 dyld: library not loaded...image not found

In your Qt project settings, under runtime settings, you will have to add the path to the ICU libraries that you compiled. There is a grid where you set environment variables, etc. The one you want is DYLD_LIBRARY_PATH, and set (or append) the path to the ICU libraries.

That will enable Qt to resolve ../lib/libicudata.46.1.dylib to the actual library file.