The building positions available depend on the building.
It needs to be an enterable building,,,,,,of course, but also the building must have a pathway LOD.
The building positions are defined as the various points along the pathway LOD which were set in O2.
Place the unit just outside the building in the editor.
in the init field of the unit put:
this setpos ((object XXXXX) buildingPos 1)
The XXXXX will be the ID number of the desired building
The number 1 will be the position within the building, the building may have more than one position, you could try 2 instead........experiment.
The position numbers start with 0.....I think.
Planck