There is an appnote for this:
https://www.nxp.com/docs/en/application-note/AN2000.pdf
Unfortunately we cannot offer comprehensive support for these legacy family (MPC5xx) since we don’t have any expert and also SW and HW tools became obsolete.
Thank you for your reply.
I'm still trying to understand how to get from scratch. For example, I used some microcontrollers which have the bootstrap option where I send a 0x00 byte and receive a response with 0xD5 by serial communication (USART), after that I can send my own firmware to control the device. What I still couldn't understand was how I can control the microcontroller. Is it the same idea as I did with bootstrap sending a byte and later sending my own firmware? Or the microcontroller has some command (opcode) where I send it and the micro will send me back the data.