Well, the CAN bootloader does not exist exactly for this device.
But you can re-use the one written for S12XE family which has the same S12MSCANV3 module integrated on the chip.
The application note AN3391 provides detailed information and SW project:
AN3391
AN3391SW.zip
Also some more additional information you can find here too:
Useful documents for building own CAN bootloader
So, this all is for free, but you would need to invest some effort to make the CAN bootloader for your application.
Regards,
iggi