Answer:
What I did on my Camaro and Honda was add brake fluid. Since it is a hydraulic fluid it is a good substitution. I was VERY skeptical because dot 3 brake fluid looks exactly like water. Throw some in and refill if it leaks a little. But it will work. I had a huge leak where I would have no power steering fluid after 2 days but it fixed it. I have been ok for 1 year now. It doesn't hurt to try.
In most situations you have to replace the rack and pinion.
If you are meticulous and have a good set of tools, you can try to rebuild the rack and pinion yourself. However, if the extent of your experience with car parts is just changing your tires, then I would not bother trying. Just buy a reman unit from any of the chains. A-1 Cardone and Atsco are good brands.
If you are brave enough to repair/rebuild you rack and pinion, here's a guide:
Warning: the job may take more then a couple of hours if you are not experienced. Not a rough job. You need to be meticulous and careful and clean.
First depending on the problem, you need the following parts:
Oil leak --> you need a seal kit
boot crack ---> you need a rack boot kit
inner tierod loose --> you need buy inner tierods
Good place to get these parts is at bestpartsonline.com or shop around but that's probably the best place.
Second, go to http://www.facebook.com/pages/Best-Parts-Online/ and look for instructions and videos for step by step instructions.