Hello,
Recently I've been experimenting with system modules.
So far I was successful in building a custom unsigned system title CIA for install using DevMenu or Sysupdater. Actual installation of the CIA was also successful using sigpatched firmwares (rxtools, cakesfw). But on the next reboot...
I know it is late but for everyone's information I write it here.
The code.bin file is compressed with reverse LZ77 algorithm which is supported by 3dstool.
3dstool -z --file code.bin
Will do the trick