The source below should compile and work on most systems because OpenCDE is relatively simple.
Please note that OpenMotif can cause certain versions of X11 (Xorg 7.5.x) to freeze. If you experience freezes on your platform please update your version of Xorg. If this is not possible this bug can be avoided by enabling sloppy mouse focus.
If you run into any trouble, please feel free to ask for help in the forums.
Since OpenCDE has been kept very simple and care has been taken to not depend on many external libraries, it is very easy to keep using any version of OpenCDE you want and not be forced to upgrade (for example if there is a change you do not like). The source code to older versions can be found here
OpenCDE 0.4.5