That's a tough question.
I normally use real OEM (link to a sliding roof model from 2012 - https://www.realoem.com/bmw/enUS/showparts?id=LL32-EUR-03-2013-E89-BMW-Z4_20i&diagId=54_0398)
The part you are looking for is "6" I believe.
If this drawing shows me anything it seems to be located around the part 2 "Coupling lock, left", so I think you need to take some covers in the trunk. My car is in the garage so can't help you just now.
