Just follow a basic compiling tutorial. Instead of using Haxe 4.1.5, use the latest Haxe, the issues mentioned in the guide are already fixed.
Note: Make sure you do haxelib git hscript-improved https://github.com/FNF-CNE-Devs/hscript-improved
before making an issue.
Just edit the source code it's not that hard (unless you can't code)...
For the non-coding people, you can mod the characters and add your own, since the positions are not hardcoded anymore. IF YOU WANNA MAKE YOUR OWN MODIFICATION/CUSTOM ENGINE PLEASE CREDIT THE ORIGINAL DEVS!