I've decided to renege on that last bit on the basis that if I showed how to fit them, someone could easily unfit them- I'm suspicious of this criminals' playground we call the internet.
So- here is a before pic of the Z3 without the hoops:
and here is one with them fitted. Suffice to say, it involved a 45mm hole saw. And the girly net still fits although it will not fold down.
They certainly look good, which is really what they're for. If I was serious, I'd get a full roll cage.