Sorry, but I don't think it's possible. The Retina display does let you choose a couple options that are higher resolution than half, but as far as I can tell those appear blurry just like selecting that smaller resolution does for you, and all it really does is make the OS treat it like that's the resolution. At best you'd only get a few things taht would look any better than just straight up setting your resolution to 1280x800. I looked around a lot and wasn't able to find anything.
@pcpu Sorry, but that wasn't what he was asking. On the Retina MacBook you have 4 or 5 scale options, a few of them make it so you don't have the full resolution possible, but it's bigger than 1/2 the display resolution anyway, and I guess it might display UI elements that are vector in the actual full resolution, but most things look blurry from what I've heard. He was asking if it was possible to do that same thing on his display, which I looked into, and I was unable to find any way to make the computer do the same thing on a non-retina display. Telling him about how retina works isn't what he wanted, he wanted the UI bigger, and the UI is entirely vector or some such at this point so it would have looked just fine bigger if he could scale.