First take out the boot liner, then there are 4 M6 bolts that can be unscrewed (10mm socket plus long extension is easiest) on the boot side of the aluminium bulkhead. Before they are completely unscrewed push on them - this moves the upper part of the seat back forward slightly which gives more space to remove the lower part. Inside the cockpit remove the seat squabs (they just lift out) then push the seat belt buckles down the way to give clearance for the lower part of the back to come out. Pull on the bottom of this lower part of the seat back to get it free and slide it out; there are two thin aluminium plates that go up behind the top part. The top part then comes free easily. You can also unbolt the seat belt buckle if things are a bit tight for getting the back out.
It's simpler and easier than it sounds.
It's also really easy to change the bevel box oil from below if you use decent height axle stands and an oil syringe to do the refill.
