How should I add the new encoding to lib/lang_??.c

[2i3r]

I'm trying to add some Arabic and Farsi encoding such as CP1256 and ISO 8859-6 to the enca.
I'm in the half way following DEVELOP.md. I've added empty arabic language just how it instructed.
Now I'm adding CP1256, but on the line

• lib/lang_??.c:
  • Add new encoding to some existing language(s)

How should I add the new encoding to lib/lang_ar.c I've created? I don't see any similar code in other lib/lang_??.c files.
From what I understood from the source code, it seems all encoding names would be added to a language by compiling data folder c codes and running a doit.sh with encoding names from data/new_language folder, which itself runs a sequence of binary and Perl codes to generate new_language.h and probably some ??.base and rawcounts.??s in the folder. is it right?!

How it should be done exactly?! do I need to compile with --enable-maintainer-mode to complete this steps?
Do you think DEVELOP.md needs a patch?