This is probably already covered in the one post I missed, but since I couldn't find it:
The little circuitboards inside the AEK2 with the ADB sockets on them that connect to the main board with 9 wires can be removed and the keyboard patched into without (de)soldering or cutting anything.
Just press and hold the white plastic thing on the main PCB down (not down onto the board, down opposite where the wires go into it. I really need to get a working camera XD ) - you'll see/feel the top part of it flex downwards a little - and then gently wiggle the daughterboard and ribbon, it should slide right out. Then you can push wires from your USB adapter (Thank you Hasu, you are awesome!) in the same way the original ones came out.
I'm guessing that Apple did this so that if one of the sockets got worn out or broken it could be replaced by the shop cheaply and quickly.
(The pinout for the ribbon is in ocodo's post here
https://geekhack.org/index.php?topic=14290.msg1559635#msg1559635, but flip it if you're looking at it from the component side of the board
