Yup, needs micro-soldering. This is very similar to neurosurgery and the micro-jumpers used are so small that a surgical microscope is actually used to install/test them.
Sometimes it needs 2 attempts before all the jumpers "take" and they are then fixed in place using UV adhesive similar to the sort used on LCD repairs.
Interestingly the work I've done suggests that in fact the signal that is missing has nothing to do with the LCD drive directly it simply detects that a panel is there and correctly installed.
This is similar to the EDID data on a laptop screen (cough OEM non user replaceable panels /cough)
If Apple wanted to they could lock out third party screens but that would suck.