The doctrine of Papal infallibility was itself issued as an ex cathedra doctrine, and other administrative points have in the past been expressed as matters of doctrine and faith. Lots of them, in fact. Look at Execrabilis, look at bulls that had absolutely nothing to do with the faith like Dudum siquidem. Popes have also used plenary powers to dissolve unsanctioned meetings of cardinals and bishops (cf. the background on Execrabilis and the Council of Basel).
As any good lawyer will tell you, the trick is simply to reframe the power struggle as a item of Christian faith. If a faction of cardinals is doing something the Pope doesn't like, he just needs to disarm them in a way that threatens their ability to continue their office if they don't desist.
And besides, he can always pack the College of Cardinals with hundreds of new cardinals of his own choosing, and get that body to enact all of his reforms.
After all, what a pope doesn't know can't lead to him controlling it. Thavis lists several examples of how Benedict was kept out of the loop on several matters by members of the Curia.
Je suis méchant.