Ok, as another user has said I created this account just to participate on this topic,
my idea is that you can use a foot paddle built into the sole of the shoe, close to the toes but far enough so that it wont be pressed accidentally, something else that can be used is the diabolo braking system.
The diabolo system is basically a small gear that will be pushed into the back wheel when weight is applied to the back end of the skate. You can see it by searching it into Decathlon