Ok, photos. I don't have "before" shots, so some steps are missing.
I started with a $10 Thrustmaster FCS mark 1 off ebay. I think it was a Macintosh model, it had a PS2 passthrough connector on the end of it. model was KP3MACFCS.
Taking the bottom off, I removed the original circuit board. There are two ribbon cables that connect the stick to the board. I desoldered them, but I'm sure there is enough leftover to cut them at the board. There was also a 5 pin connector that would have run out to the PS2 connector and the computer, it just pulled off the board.
Remember, you're looking at the bottom of the stick. You can see the two original ribbon cables - one for the stick, one for the pots. The stick has 9 conductors and comes out of the bottom of the stick support tube in the center. The pots get 4 conductors and come in from the bottom left in this view. To connect to the PC, I just hacked a usb phone cord in two and spliced it in to the original keyboard cable, so I could keep the original stress relief. The splice is ugly, but it works.
Board views. I added one diode on the common ground and soldered the original cables straight in. The pots are just too easy, wired exactly like the common samples images earlier in this thread.
This is what the stick buttons and hat switch looked like on mine - colors all fed into the green common wire.
This is how I hooked to the pro micro.
Once again, three cheers for Mega_Mozg!