First of all, make sure you have your radio code to hand then disconnect the battery and go have a cuppa for 1/2 an hour.
Feel behind the wheel and you should find the holes that house the bolts holding the airbag on.
undo these, their most likely torx headed bolts.
onclip the airbag wire and any wires that need unclipping.
Undo the nut holding the wheel on but leave it on a few turns. (Don't take it off completely then yank on the wheel or you'll get a face full of wheel and it hurts!! Trust me, I know!)
with your palms strike hard from the back of the wheel until it comes loose.
now you can remove the nut and the wheel.
the new one from a later facelift will fit, even an early XF wheel will fit although I think the wiring may be different, not sure on that.
Refitment is the reverse of the above.
Good luck.