Hopefully this is enough information to make fitting the IS/Altezza OEM armrest easier. It took me about 11/2 hours but I was taking lots of pictures at the same time. My car is a 2002 Altezza Auto.
First remove the lid from the old box. Just two screws hold it on.
Then pull out the felt base and remove the two screws at the bottom of the box.
Now remove the handbrake gator. Just pull it straight up and the two tabs will pop out.
Removing the ashtray is easy enough but the panel in which it sits is a little delicate as it is attached to the chrome ring around the gear stick. I managed to remove it without using any tools. I did it by first lifting the forward part of the ashtray recess with one hand and then lifted the rest bit by bit.
Disconnect the cigar lighter and lights then remove the panel.
Remove these two screws.
Pry off the caps and remove these two screws (one either side)
These nasty little tabs (one either side) were the hardest bit for me. The easiest way I found to release them was to reach inside the console and pull them in towards the centre of the console and pull the console back at the same time. It did take quite a bit of effort though. If you have a mat over the transmission tunnel in the back of the car you need to remove it for clearance. Once they are free, carefully lift out the console.
With the console upside down remove the rear cup holder draw and steel housing. To remove the draw you will need to push down two steel tabs. Once the draw is removed lift the tabs back up (as pictured)
Remove four screws and take out the draw housing. Remove the remaining two screws and the old box will lift out. Picture shows the new box in place.
Back to the car. The bracket over the handbrake cable can be removed. The bracket is no longer needed. Keep the bolts.
On my car there were two sticky pads covering two more threaded holes that are used for the armrest tower. They're not really needed but I had two spare bolts and so went ahead and used them.
Bolt down the armrest tower with the stamped arrow pointing to the front of the car.
Carefully replace the console. Replace all the screws to fix the console in place. Insert the magnet hole cover.
Install the hinge cover making sure that the five tabs enter their receptacles (three on the bottom and one on either side)
Install the armrest onto the hinge. The bar arrowed in the picture needs to drop into the slot at the top of the hinge.
Now drop the armrest down and then insert the bolts (they are shoulder bolts so you can't over tighten them). Do this from the back seat with the front seats all the way forward.
The only thing left to do is press on the two caps. They are marked up for left and right and with the arrow pointing straight up they will go on easy.
Hope this helps a few people out.