I'd advise new O rings for the Hi pressure port where the lines go into the pump. and a NEW pump body O ring as well.
Removing the reservoir is mess, drain it as best you can, have a long piece of scrap hose that fits the return nipple, long enough to hang to a bucket or container on the ground, slip the return line off...then quickly slip it on...drain it!
To remove the can/reservoir remove the HI pressure line from the large 1" (IIRC) fitting on the pump, then remove that large fitting carefull you will have some small parts want to come out and they are spring loaded, a pressure release valve or something. set them aside in a safe place!
Now you can begin to twist back and forth the reservoir and work it off the pump body. Once past the O ring it's a easy pull. Remove O ring and replace with new one, lube O ring prior to install and very light lube on inside new reservoir. Simply slide new part in place carefull not to eff new O ring. Re assemble the small spring and part and place in pump, then install new O rings on the large fitting and install it too.
BTW, NOW ....NOW is the perfect time to install some type of filter in the system ...Like here
http://magnefinefilters.com/Magnefine-3-8-Magnetic-Inline-Power-Steering-Filter-R038M-P.htm
In for the penny in for the pound...right?
Anyway it's all quite simple remove and replace at this point, I'd jack up and block front end on drivers side, remove front wheel to make access a tad more simple from fender well too btw.
Good luck on install it's not all that hard.
Al