Pretty easy really.
Have a good read of this thread: https://www.1addicts.com/forums/showthread.php?t=1358509
Basically, unscrew the paddle assembly from the wheel, unscrew the paddle from the mounting base, remove the plastic hinge pin from the old and new paddles and swap them over and screw everything back together. As you keep the original circuit board base.
I kept the rubber pad with the conductive buttons from the f series paddles but cut off the spring guide as the original base has a plastic spring guide and also swapped over the f series spring as it is stiffer.
Result is an OEM look and a much nicer feeling paddle actuation.
I just bought the replica f series paddles you see on eBay or AliExpress, quite surprised at the quality, then again I wasn't using the circuit board on those ones.