Bootstrapping a new HAL:

Good morning,
I’m trying to bootstrap a new HAL, I would like to use STM32F0207 that has ethernet on board.
I started following this guide

but it misses a lot of things… I’m not able to compile almost anything… So I tryed to edit a lot of file (in STM32FXXX folder) and I added PLATFORM_ID == MYID even it is not documented.
Does anyone have a guide or something to help me?
As I said before, the documentation lacks…
Thanks a lot, Flavio