Cross-Lib can be used by just cloning the repository and install some minimal prerequisites (for most cases just, python, gcc, ncurses):
https://github.com/Fabrizio-Caruso/CROSS-LIB
Cross-Lib alone can be used only to build games for the native terminal console. So it won't allow to cross-compile built-in games, nor built-in examples or new projects for vintage systems.  In order to cross-compile and build projects for vintage systems you will also need to install the required cross-compilers.

Detailed instructions are in:
https://github.com/Fabrizio-Caruso/CROSS-LIB#installation-of-the-tool-chain