My ps fluid looks pretty bad. What's the best way to replace it - without disassembling the entire system?

The return hose to the p/s reservoir is the top hose. Disconnect this at the reservoir. Using a small piece of solid pipe, clamps and some clear vinyl tubing, make an extension that will direct the fluid into a container or bucket. Get a quart of new fluid (I use Mobil 1 synthetic ATF, which works fine even though your manual calls for Type F.) Start the car and have a friend cycle the steering wheel back and forth. As the pump moves the old fluid out the hose, refill the reservoir with new fluid. When you've just about used up the quart, you will have completely flushed out the old fluid. Re-connect everything, bring the reservoir up to level and you are back in business. If you suspect metal contamination in the old fluid, place a strong magnet on a thin wire into the reservoir and leave it there for a week, removing it to check it and clean it off.