Well, it could start in one or two states. They could agree to set up an body independent of the legislature to run and oversee voting processes, including disputed returns, and give them the power to redraw electoral boundaries as necessary after each census with very strict guidelines about how they should be drawn. If, or when, the benefits become obvious to the voters then perhaps other state would be obliged to follow suit by popular demand. When enough states are on board, these separate authorities could be linked up in a national system.