This isn't exactly a highly technical installation--all that's involved is preparing three bits of tape and pressing hard, but seeing as it's a semi-permanent installation it's important to get it right!

Place the armrest roughly in position but upside down so you can see where the pieces of tape will attach to the existing console

Now try it right side up. Have the handbrake up to ensure it doesn't foul.

Make sure it doesn't obscure the little tray in the rear

Which on US models is used to house the BMW Assist module

Now remove the pieces of tape, say five 'Hail Marys' and press hard

The armrest doesn't obscure access to the rear console storage

And it hold the equivalent of three small digital cameras
Tim