Alan, if by rear steer you mean toe then go slightly negative on the right rear or another way to put it would be go for a "little" toe in. I don't think you will ever want toe out on either side in the rear.
My reasoning may be a little rusty but as you accelerate forward thru the turn and transfer weight to the rear the right rear is still trying to force a left turn instead of trying to push the rear end back under the car.
Ed M.