The handbrake assembly looks fairly straightforward according to this diagram.
Have you tried giving the handbrake lever (4) a gentle tug/twist to see if it moves? Looks like it should just slide off, although you may need to remove the gaiter (3) first.
Is this the handbrake cover you mean? Looks nice. Would think that if BMW sell it as an 'accessory' then it should be relatively easy to fit (famous last words!)
