The passenger side can be done with the manifold in place. The drivers side is a different story there is a clip that is fitted on the bottom of the arm which is impossible to remove/clip back without taking the manifold off.
The swirl flap motor has to come off, the plastic air intake on top of the engine has to come off, couple of the metal fuel lines need moving then intake manifold comes off and it literally takes seconds to replace the parts.
It took me about 2 hours or so to do it, a mechanic would probably do it in half that time.
The arms can be done with everything in place, but I tried just changing the arms only at first and the engine management light came back on. The most wear when I took it apart was on the actual plastic shaft that sits in the manifold and drives the flaps.
Once I replaced all the parts the management light has not been back on, its been about 2 months since.