Handicap Equipping a 2001 Prius

I am thinking about buying a 2001 Prius. However, in the probably near future I will need to handicap equip the car. Notably power assisted braking (I'm not sure if that is the correct terminology). To make the brake pedal lighter to use. Is this possible in a 2001 Prius? I know the Prius brakes partly on its electric motor so I wonder if it is possible to strengthen the hydraulic braking without upsetting the balance between braking on the engine and braking hydraulically.

Is the 2001 Prius already drive by wire?

Is there space somewhere, like behind the bumper, for a vacuum pump?

Looking for answers....

I have a modification company looking into this for me but they can't give me an answer soon.

 

I live in The Netherlands. The requirement to drive a car is that you can deliver 600 N (60 kg) of pressure on the brake pedal. This is to be sure that you can stop the car in case the hydraulic brake system fails.

Now my question: what will happen if the hydraulic brake system fails in a Prius model 2001? Will the force needed on the brake pedal to stop the car increase or not?