Can we add SJA1000 CAN controller IC to the ECU which don't have CAN protocol with S08MP controller? What is the difficulty in adding CAN controller IC to the existing ECU?

[parthasarathipa]

Can we add SJA1000 CAN controller IC to the ECU which don't have CAN protocol with S08MP controller? What is the difficulty in adding CAN controller IC to the existing ECU? 

I am working on a project where CAN protocol is not available on ECU. TO add CAN protocol, I am planning to add SJA1000 CAN controller IC to the existing ECU. Please help me out on this.