For the brake and clutch you pull the rubber caps off and replace with the aluminium ones - they are extremely easy to do. The accelerator doesn't have a rubber cap by default so the aluminium one fits on top of it - it's tricky to do, but there is a technique - you have to hook in one corner first diagonally, rotate the pedal so it's all on one side, then push down the other side. It's hard to explain without it in front of you though!