Is there a how-to on adjusting the rear brakes on these cars?

There is a procedure in the service manual, but that requires a special tool to measure the diameter of the brake shoes as installed. This is because GM saved a few pennies by not providing an access hole for a brake adjustment tool like Ford and Chrysler. Without the special tool, you basically have to remove the drum and adjust the brake shoes outward until the drum cannot be slid over them. This is a repetitive process. When you can't slide the drum over the shoes, back the adjuster off slightly until you can push the drum over them. That gets you close enough for the self-adjusters to complete the adjustment.

Someone else may have a better way to do this, but this procedure works for me. I've tried drilled/slotted rotors and ceramic pads, figuring that the rotors would dissipate heat better. After 10K miles, though, the rotors began to show signs of warpage. That'* when I concentrated on the rear brake adjustment. Haven't had much warpage problems since.

ive always been told that the way to adjust them was to go fast in reverse and then SLAM on the brakes and i believe that the self adjusters are supposed to do the trick, unless of course the adjusters are stuck then this wont work

I do not know what year they implemented the self-adjusting, but that would be correct if his year came with it. Reverse and brake hard.

and a BIG x2 on bedding in the rotors.

I've done the reverse and brake hard repeatedly just in normal driving.

I've also done the manual adjustment many times.

Personnally, I'm trying to break the habit of braking hard then keeping the brake depressed as I sit at a traffic light. Its the last thing I can think of.

4K on the frozen Power Slots and no problems yet.

When I adjusted my rear brakes manually, the car had noticeably better braking at once.

Self-adjusters don't.