It's very easy bud
The hardest part is making sure none of the interior trim gets damaged.
The window controls:
Assuming the 2012 controls are of the same design as my S2 Grande, these can be eased out without too much hassle with a flat-bladed screwdriver with some masking tape over the end - there is a small recess in the front of each panel where you can pull the front of the panel up. There are then two metal clips around each side that hold the panel in place, so work your way around the outside edge and the controls should come free. The plugs can then be taken out - if you're painting the panel, take the control buttons themselves off the actual fascia again by undoing some clips, makes the job much easier.
The steering wheel controls:
These can be taken out again with a flat-bladed screwdriver, but I'd advise removing the horn fuse first, unless you want to scare your neighbour's cat half to death like I did. Try working your way around the outside (closest to the doors, respectively) of each side, as the controls themselves protrude underneath the steering wheel centre/horn push. Care should be taken not to damage the rubber, or leather especially, of the steering wheel.
The plastic fascia should just pop out - it has no electrical contacts which is handy, the piece you can see simply sits on top of a rubberised relay that is operated by the pressure of the keypad; careful not to damage the rubber part though, as it is only held on very loosely by two wires. You can then do what you like with the plastic fascia - if you're painting it, the buttons all unclip from the main body, but can be a little fiddley.
Hope this helps
Adam
