You really only need power steering below 10 mph. You can turn it off above that speed. That's where an electric pump will really excel over a belt driven pump. If you run it all the time then there is no benefit since the added electrical load is translated to your alternator. This is even less efficient than driving it with a belt and that's one big reason why it took so long for car companies to consider it (not to mention that we're butting up against the limitations of a 12v system).
My Civic was fine with manual steering until I upsized the wheels, got some sport tires, lowered it, and then got a smaller diameter steering wheel. All this benefits handling substantially but it sucks for parking and low speed U turns. Endyn actually made an electric power steering pump for the Civic that was part of their supercharger kit. They stopped making the kit but I wonder if I can talk them into making me a PS pump.
I'll bet it's pretty difficult to retrofit EPS into a non-EPS vehicle. My Civic has it and it's designed to assist you heavily at low speeds and barely at all at highway speeds. That sort of logic is controlled by the ECM using various sensors... I would think it's not a plug-and-play type of device.