unbrakonøkkel = hex key
fjør = spring
This is all taken from
Montere metall sleide og ramme på p226
2. Warns you to be careful when taking off the grip, as the right side triggerbar spring easily get lost, and also the decocker.
8. Now you can remover the hammer unit. As you can see the screw on the right side is removed. This will only have to be removed if you are disassembling the unit. That will not be done in this guide, and is not necessary for this upgrade.
12. This warns you that the trigger unit is pretty tight-fitting in the frame, so pry it out carefully with a small flat head screwdriver. Also the little spring on the left side is completely loose.
16. The trigger unit may need some filing to fit. If the plastic lever doesn't turn easily, you'll have to lift the trigger unit slightly at the rear.
20. The decocker is a lot easier to fit if the hammer is cocked.
I think that covers about all that you can't easily tell from the pictures.
Do note that I haven't done this myself. I just stumbled over that page when trying to decide what GBB to get for myself. I thought this all seemed like a lot of work, and just got a KJW p226 full metal instead. Had I known how fast that would wear, though...