Before changing the P/S fluid, make sure you have a DEEP SOCKET 10mm; not the regular size. You'll then be able to remove a nut, followed by a spring and then the filter. A pair of needle nose pliers comes in handy for removing the filter. A turkey baster is great for siphoning out the old fluid.
There's also a gasket that goes around the inside of the top cover. In my case, the one that fits is made of rubber - all others are too big and to date, the dealer is the only place I've ever been able to find the correct gasket.