Well that was an adventure for me.
So the FV-T919 Bluetooth cable ends in a USB2 header as I said before. There are only two keys in that connector; one red wire in pin 5, and one black one in pin 3. Using a pinout diagram of USB2, pin 5 is D1+ and pin 3 is D1- (makes sense, red is positive, black is negative). So I removed the keys in order to give myself as much wire as I could. I then used a wire stripper to remove the key and some shielding. Then I took the spare Bluetooth cable for the OEM Bluetooth chip I had laying around. I cut off the end connecting to the chip itself, leaving as much wire as I could get connected to the board-side connector. Removed the two wires that the guide said were "useless", and stripped the A and B wires. I then had to make my decision, which was positive and which was negative. I chose A as positive because I dunno, it just seemed right. Spliced them, ghetto-electrical taped it together, and connected the main PCIe card and the wire up to everything. Turned it on and bam, I got AC WiFi and BT 4.0/LE.
I did have to removed the OEM Wifi chip to get everything to work flawlessly however. For some reason, turning off the OEM one turned off the PCIe one. It also affected Handoff/Continuity, and Apple Watch unlock. I did have to sign out of iCloud and back in to get those features to work however. All in all, I'm glad I saved $140 on a OSXWifi card; I can put that towards more RAM and new CPUs.