Hi Frederik
I cannot say anything on how you can order the parts, I just handled the ordering from the source in the US to Europe, but concerning the application, it is rather easy. The parts are attached with 3M automotive adhesive tape that is already applied to the individual trim pieces. A major factor is very good cleaning of the B and C pillars of your vehicle. The best way ro do this, is starting with a window cleaner (I don’t know whether they sell Windex in Europe, but that is what I used), and once all the visible debris is removed, and the pillars a re dry, you should wipe the surfaces down with something like isopropyl alcohol, and let that dry again.
After that you remove part of the line from the adhesive backing on the pieces (the best would be the top), and carefully adjust the trim with the supporting surface. Once the adjustment is correct, you apply some pressure to the exposed side of the trim, and it will adhere to the vehicle (after this, it is almost impossible to remove the part again from the vehicle). Subsequently, you pull the now hanging down section of the liner further down, and thus remove more liner away from the adhesive. Once the liner is fully removed, you apply pressure to the entire trim piece, to attach it fully to the vehicle pillar. Following this action, it is recommended to used a soft cloth or paper towel, to evenly press the piece the piece onto the pillar in its entirety.
Please be informed that the vehicle and trim temperature should not be less than 18 ºC or so for best adherence.