Hi,
There is no AN which implement CAN bootloader. However it is still a serial communication so you can use any CAN example code and cover it with your higher level communication protocol.
( https://community.nxp.com/t5/S12-MagniV-Microcontrollers/LAMA-s-S12XE-unofficial-examples/ta-p/11007... )
The main problem to create an example is the programmer site which requires some code on PC side or any protocol translator/interface if you use another protocol on physical line (for example UART/CAN/UART, USB/CAN/USB, ….)
The philosophy of data processing and the programming algorithm remain the same.
There is, however, AN2546 (search for it in link presented bellow) which can provide you some more info but it was designed for old families. I mention it only for inspiration.
https://community.nxp.com/t5/S12-MagniV-Microcontrollers/List-of-MagniV-and-S12-X-Application-notes/...
Best regards,
Ladislav