I have got the CDE desktop to compile on Ubuntu 14.04. I found this website: https://www.ics.com/blog/retrocomputing-motif-and-cde#.U-840NaKhqg, which in turn lead me here: http://sourceforge.net/p/cdesktopenv/wiki/LinuxBuild/, a WIKI which contains the build instructions for Ubuntu 14.04. I followed this guide and the build worked perfectly. This is very cool indeed. The performance of the CDE desktop is very good on a comparatively fast machine considering the technical specifications of the old hardware it used to run on. Any CDE fan should give this guide a go, this really does work when setting up a custom Ubuntu installation. You could create CDEbuntu and release this custom distribution into the wild. There is CDebian, this is a very old Linux distribution of Debian that includes the CDE desktop, but using a more modern Ubuntu distribution is a much better idea. Far superior hardware support.
The only problem is that I cannot get the dtlogin login manager to run on boot, I changed the default value in /etc/X11/default-display-manager to /usr/dt/bin/dtlogin, but I do not get the thing to load. I think that it takes time to load itself up. still, the actual desktop when loaded does work very well. I just run sudo /usr/dt/bin/dtlogin as root and the login manager load ready to accept my login details. This desktop used to be a proprietary release, but now the open-source release has hit the Internet and everyone is excited to be able to use a free version of the venerable CDE desktop environment.