I have the same question. Could not find any answer in help, assist and community for this. Even during peak season no live help available. 

To generate the Form 5119, go to State and Local > Taxes > Michigan Cities.

On this screen, choose "Cities" from the upper right.  

Once there, choose Detroit in the City Name field.

Then in the Residency field, choose from the list what option you want.   Any of the nonresident choices will generate the 5119.