Uruk mate, its very easy.

Remove the old handles from the door, turn them over and have a look opposite where the key enters the barrel.
There should be a screw - undo this and you should be able to slide out the barrel. You'll have to be careful as there is a spring attached to allow the key/barrel to return to the horizontal position after unlocking/locking.
Either note which way it goes or look at the handle from the other door.
As long as your careful then you won't have a problem.

I have the mk3 style handles on all 4 doors and they work great and look good - a very subtle mod. Keeping it original with a hint of modding
