Ok, Just give me some time. I'm struggling with installing Windows 10 and Office 365 on the machine at the moment.
Installing on the same SSD with Big Sur and High Sierra didn't work out.
Had to sort out with Windows Home on an USB enclosure before moving it to internal.
I will post the photo of 2 positions of the plug.
1) General view. For the antenna, IPEX1 to IPEX4 cables, I used 2x 5cm cables, and 1x 15cm cable. Took me 2 hours just to firmly attach the IPEX4 jacks. Had to throw away the same amount of IPEX cable because of my clumsiness.
View attachment 1784948
2) The premade jack (white) in its position. All its way to the right of the female jack. Red is D+, Black is D-. I guess in my case the 3.3V line is the 3rd one from the right. The white jack can be plugged in all the way to the left. But then the blue tooth is not recognize (wifi still good).
3) A little blurred, the premade jack next to the stock USB cable connecting to original BT unit. Matching with the red-white cable, then cable color should be Green = D-; White = D+; Grey (purple) = 3.3V. I don't plan to turn-off wifi anyway, so I didn't modify 3.3V line. I'm just happy it worked plug-n-play. The wire are too small to my eyes for any modification.