From what I can tell, the best way is to first adjust the rear brakes so they grip evenly.
Jack up both rear wheels and spin one while slowly tightening the adjuster until it starts to drag. Back the adjuster off 2 clicks. Do the same on the other side.
Next, pull the clevis pins on the rods that go to the wheels so you can get them even.
Make sure the handbrake lever is fully released. Adjust the main rod linking the handbrake lever to the rear pivot by winding in or out one of the clevis yokes until the pivot at the back axle has its maximum travel. Adjust the 2 rods that go from the pivot to the wheels so they have the same "slack" and refit the clevis pins.
Done.