I'm not sure why a steady state economy would be desirable. It basically sounds like a central planner's wet dream with the impetus of saving the world (birth licenses, resource consumption restrictions etc). Strict control of natural resources in order to create artificial scarcity and influence the price level and lower consumption basically. It would simply mean that that wealth has reached its maximum limit, and that one can no longer increase production. That said, I think it's impossible, given that the entire point of innovation is to make more out of less. In other words, if we maximized the use of the Earth's natural resources (and were incapable of getting these resources elsewhere) then it would make more sense that we begin to utilize these resources more efficiently, increasing production of goods per resources used. This is what we have been doing for millennia. Take for example the agricultural revolution: the same plot of land could grow many times the amount of food it did originally. This allowed for a massive boom in population. I'm not sure why it's not possible that this would happen again, in any given resource that could be produced by man.

There is no human or group of humans or computer or group of computers or group of humans and computers that can manage an economy as it can not take into account consumer demand and is even less able to account for changes in that demand. There are far too many variables for any computer or government to hope to control an entire economy. So any attempt by humans and computers to manage an economy by constraining demand or supply or both is doomed to fail as this group of humans and computers does not have information available to actors in the economy. Investigate the calculus problem / economic calculation problem = the reason why intervention and central planning always result in the misery it claims to fight. "Human Action" or "Economic Calculation in the Socialist Commonwealth" by Ludvig von Mises are good places to start.