I don't really know if my way is the right way, but it works for me. I pull the return line (the one with the clamp) off of the pump resivoir, use a small piece of copper pipe and a longer piece of tubing long enough too reach a drain pan under the XJ. Start it and turn the steering wheel slightly left and right as a helper pours fresh fluid in the filler hole on the pump resivoir. If the resivoir runs empty shut down the motor.
I usually run it for only 10 seconds or so, then shut it down anyway. If the resivoir does run empty, hook the return line back up and turn the steering wheel from lock to lock, this usually reprimes it and gets all the air out.
Pulling the air box out, makes access and the process fairly simple.