Annihilation's way means (as I think) that your unit will be randomly chosen when you build it, just like the three technicals. (AZH please correct me if this is wrong).
But, if you want the AI to always build them in your map (not randomly chosen) you can always import the skirmish scripts to small map, and add a new team (with its conditions and rally point etc.) or just modify an original team to make the AI build them.
I hope I(am/was) useful at some point.
Originally Posted by: UTD^Force