(working title)
If you just want to use jjjj, just add the repo http://cydia.r333d.com and install "jjjj" from there.
This is all of the app code for jjjj. This repo is exactly the same as what you'd find in /var/lua/jjjj.app on your device.
This app is written in Lua (using the LuaJIT ffi). There is some C code though, which can be found in jjjj-core.
Entrypoint is init.lua. App launch entrypoint is main.lua. A lot of the app logic is in the pages directory. ObjC-to-Lua abstraction stuff is in ns and ui. deb/repo related stuff is in deb.lua and repo.lua.