Your sure your power steerings not working? It could just be that 8 inch spoiler on the back hauling your car's ass around.
The only thing the Haynes manual talks about is replacing the power steering pump, you may want to check the amount of fluid you have as well.
Only a few cars came with the 4ws option, and I don't know anything about it besides the fact that back in the day if the rear-rack got damaged you had to replace it all and that cost lots of money.