Hi Andrea,
The S12ZVL MCUs contain MSCAN module, but CAN physical layer is not available on this device. So, you have to use external CAN transceiver.
CAN Transceiver and Controllers|NXP
You can take a look at AN4975 - Using MSCAN on the MagniV Family
https://www.nxp.com/files-static/microcontrollers/doc/app_note/AN4975.pdf
SW:
http://www.nxp.com/files/microcontrollers/doc/app_note/AN4975SW.zip
I hope it helps you.
Best Regards,
Diana