one thing to remember! Thjhe white inserts will make the mushroom shaped dome that snaps into the panels MUCH more difficult to remove. I opted not to even use them, which is also what Dan Caron recommended. I am glad I did not. the trim holds plenty without the inserts. Also, since the profie of the trim is the same whether its on the fenders or the door, it doesn't really seem to matter if you just use the orange ones alone or both the blue and the orange. I ordered mine directly from MB, and they actually only had the orange ones available anyways, while the SLS kit shows both types on their website.
Do what you need, but mine are just fine the way it they are without inserts and with just one color.
They trim snaps on easily if you just lay it over the top first and gently push it downward (vice versa will work as well). If you want to make it slip better use a drop of dishsoap on the groove of the plastic pieces, but I doubt it would be necessary