if i had took pictures of me doing mine then i would have done a
how to thread!
Basically all you need to do is cut out the recess piece
Bring it forward to where you need it,
Prop it up from behind so it doesnt move, or even use brackets screzed into the bumper to keep it still.
Plastic weld the edges
Now when your smoothing out the plastic welded pieces use a Filler called PLASTIC PADDING, its in a silver tin with a yellow lid, its filler specially for plastic and is really flexible so it wont crack half as easy as regualr filler or fibreglass.
Then when you have smoothed over the lines enough, start using regular bodge to get a better smoother finish.
As for the moulding, i haven't done it yet, but it looks hard. just got a new one from SEAT today so i wil take images of this as i do it!!
Im sorry for the gashness of this so called 'Advice' what with lack of pictures etc.