Sorry for necro'ing this thread. I am in the latest version and I can SM edit the population of the colony but despite quite a lot of looking cannot find a way to add installations as SM. I am sure I could in 1.95 but either its missing or I failed my perception check.
Open the Econ window with SM mode on, go to the Civilian Economy tab, and look on the leftmost of the three panes.
At the top, you have a dropdown for installation type.
At the bottom, you have SM buttons for Add/Edit/Delete.