I'm pretty sure that the car would still have to comply with the ADRs. You could probably order a car in Euro 4 spec, which has some similaritie to the OZ spec, with high roll bars and then have any other mods made to comply with the ADRs which would then have to be certified by an approved engineer.
Chances are that at the end of the day you would not save much money and you would be pretty much on your own with any of the many warranty issues that are common, and common knowledge, with the M3W.