I came across the same problem in a mission I'm working on .. the best I could do is get a few guys on the roof and on the fire escape looking walkway on the outside of the building...
seems that you can place vehicles inside.. but put a unit right next to it and he's on the roof
There seem to be no position numbers for this building... how the hell did they miss that one? LOL
Seems a BIS oversight will prevent us from using the building to it's full potential '
*EDIT* Negative there on both accounts there Mike B ...
The WP thing does not work on this building.. and setpos also does not work... that second syntax you mentioned might be the key here... adjusting from relative position *EDIT*