Installing KDE4 development files in 2020

I want to compile the Oxygen-transparent project which requires KDE4. I've tried building and installing the KDELibs 4 Support package , but still there's no kde4-config in my system. Here's the output of running CMake in the Oxygen-transparent repo :

CMake Error at /usr/share/cmake-3.10/Modules/FindKDE4.cmake:60 (message):
  ERROR: Could not find KDE4 kde4-config

Where can I find that file ? Is it possible at all to install such an old program in newer KDEs ? By the way I use KDE Neon dev edition 5.19. Thanks in advance.