How to initialize driving support ECU?

I don’t have any information about replacing ECUs with parts intended for a different model or country; you do this entirely at your own risk. Consider that the systems or features involved may seem to operate as you expect, but they might not work properly under all conditions. There may also be safety or legal reasons that Toyota did not include certain features on vehicles built for sale in your country.

That said, in the U.S. edition of the Repair Manual, available by subscription to techinfo.toyota.com, the instructions for removing and installing the Driving Support ECU mention only the initialization procedures for the steering angle neutral point and back door lock, which are to be done any time the auxiliary (12-volt) battery is disconnected, plus the SRS diagnostic check required after reinstalling the lower instrument panel sub-assembly. I couldn’t find a published initialization procedure for the Driving Support ECU itself.

The Repair Manual does have adjustment procedures for the front camera and for the millimeter wave radar sensor assembly. I don’t know if these procedures would be needed if the Driving Support ECU were replaced with one having different software.