I don’t think there is any way to set everything up well without enabling mipmapping form C++. The modification to the class is very simple, it’s a shame Epic hasn’t implemented it yet.
The article mentions using shader based supersampling, which can be done in Unreal through the material editor. I’ve implemented it and it is an significant improvement over regular mipmapped. I think it still needs mipmapping enabled to give any benefit though.
200% zoom, stock on left, mipmapped on center and mipmapped + RGSS on right
The link above lets you copy the code into a material blueprint.