This was too easy. No screws need to be removed to extract the keyboard, all needed is to pop two tabs with the fingernail and the keyboard lifts off the palmrest very easily.
The original keyboard uses one FPC but the backlit keyboard uses two: One for the keyboard and the other for the backlight. I could see the connector for the backlight on the motherboard. Removed one connector and plugged two in, rebooted and boom. A backlit keyboard!