Adjusting parking brake

Is it possible to adjust the parking brakes without taking to a mechanic? I remember how easy it was with older cars that had rear drums. But I read that with a manual tranny and discs all around, a pro mechanic should adjust them.

My truck has been making groaning noises when I am parked on a boat ramp, parked in first gear with parking brake set. Today, I had to get back in twice to pull the handbrake lever higher, and then it was hard to release. I don't like the prospect that the brake not holding well put strain on the transmission, either.

I am going to buy some wheel chocks as back-up but want to get the brakes adjusted, too. The truck has almost 88k miles on it and the rear pads were replaced once, years ago. Brakes are working well otherwise.