Only things you need is BCPKG2-1-Normal-Main.bin, BOOT0.bin, TSEC & SBK Key from a nand dump.
Written in pure C#, no hactool.exe needed, comes with source code.
- link removed, get updated version here:
https://gbatemp.net/threads/atmosphere-layeredfs.507653/page-2#post-8059831
- copy BCPKG2-1-Normal-Main.bin & BOOT0.bin into "Data" dir
- run KeyDumper.exe
- enter SBK, TSEC and optional SD SEED (you can also edit the Settings.ini)
- the program should generate a keys.txt and decrypt all needed files
- now run KernelPatcher.exe, it will use the decrypted Kernel.bin and generate a kernel-patched.bin