Go them in over the weekend. I think I can feel my fingers again now.
It turned out much easier than I thought.
Basically I dissembled the car side connector from the projector donor car and put in my wires with new terminals crimped on. Since we're JDM, all the wire colors match and it's easy to see where everything goes. The only oddity is the low-beam ground cable and extra wire on the parking lights.
The ground cable I stripped and jammed in underneath the correct terminal in the connector. Once it's reassembled and taped, it wasn't moving anywhere. The extra wire for the parking lights just got clipped and taped to the wire bundle so they don't short against anything.
It seems you only need a ground cable on one of the headlights and it takes care of the whole circuit.
Also, I found out my front end seems to misaligned and had to take the locating pins out of the headlight so I could screw it down. Once I aim them it should be fine.
Haven't driven it at night yet, but the difference in the parking lot is apparent, there's much less light lost off the sides and it's hard to see the light are on except if you're looking directly at them. So far so good.
Overall I'd say it's worth the trouble if you can get a cheap set
The terminals look like this. I got mine from Jaycar and they were brass
https://www.ozautoelectrics.com/media/catalog/product/cache/1/image/640x480/5e06319eda06f020e43594a9c230972d/q/u/quickcrimp_non_insulated_female_crimp_terminal.jpg