I live in Sweden so my English is perhaps not the best, but hopfully you probably will understand. Anyway this is how to do it. I have to do it each year in order to fulfil the Swedish car control. I have a 94 with disc. There is a scruw in the brake piston. That scruw is for the machanical brake, the parking brake, and then you have the hydraulic, which is for the normal brake. You will not see the scruw, because it is inside the caliper and attached to the arm via a small rod that twist.
Lift up the rear of the car and take of the rear wheel. Not necessary, but it makes it much more easy. Make sure you have some support under the car so it does not fall over you.
Push and release the Parking brake pedal. Go back to each rear brake caliper and take a big scruwdriver or something like that and push the arm that have the cable attached to it as much back as you can. It does not go that easy the first time. Go back and push and release the parking brake pedal again. Back to the rear wheels and push the arm of each caliper back. You have to do this a cupple of times. You will now notice that the arm goes better and better each time. When you have the car up make sure that all the wire goes as they should. Just behind the diff is the coupling from the cable that goes to the front and the cbles that goes to each wheel. When you have the caliper running as they should then you adjust the length of the cable. It is a clip that hold the wire connection. Push it down adjust and pull it back.
Try to make sure that the parking brake pedal goes as it should and have enough of travel distance etc. Hard to describe, but you can feel it when you sit in the driver place.
The reason of why you have to do it several times is that the scruw will sometimes not adjust as it should and the arm can have some rust so it does not go that easy. You really have to push the arm back hard the first times. There is some oil is spray cans that help loosen rust. Spray on the arm while you do this. It is in more or less all gas stations etc. do not cost much. Use it and use it several times on the arm when you adjust the parking brake. You will see what I have dscribed when you stand att the rear brake. It is very easy to do it.
If you have someone in the car while you push the arm at the brake caliper this should not take tonger than approx 20 - 30 min from when you start to lift up the car until it is back on its wheels again.