OK.
digging more in to it, it looks a little bit more complicated.
if you want to use your horseshoe piece (part#19), you will need also to replace the air vents (part#18)
Porsche Boxster Accessories Dashboard Trim Parts
and also part#2 in this diagram (the air channels behind the air vents)
Porsche Boxster Heating Parts
looks like the switches will seat honorarily with this setup (to answer BL question)