Question: how to import kmz into microstation?
Answer: Use Sketchup Make to import the Google Earth KMZ file. This will make a . ... 
In Sketchup > File > Import > in the Import Dialog choose File Format tab and select "Google Earth File (*.kmz)"
Create a new DGN file in MicroStation > File > Import > . ... 
Check and see that all elements are OK after import.