I would think it would be possible via the repair function. As multiple buildings are damaged from seiges and such, those buildings can all be queued and repaired simultaneously. Now the trick would be to swap the repair function with the construction function and to add turn timers to the "build via repair" function. You could then in theory have multiple building projects going on at once, eh.. pending its not hardcoded that is. I dont mod anymore, as i play WoW fulltime and MTW2 is a part time hobby. However if i should see such and idea turn up in a mod in the future you better believe you owe me royalty rights