Never done it on mine yet, but I'm seeping fluid from flexible return hose, so that will happen soon enough.

Here's what I plan to do:

1: Drain fluid from the reservoir by removing the leaky hose and aiming it into a container. Reattach new hose.

2: Replace the filter. We're lucky to have one. Most cars do not.

3: Refill the reservoir with fluid. I'll get mine from the dealer. I'm sure that you can get the proper fluid elsewhere, if desired.

4: Start the engine and listen for any noise from the pump. With the reservoir full, it shouldn't run dry for very long, if at all.

4a: See below.

5: Check the fluid level. If it appears to be at a safe level, drive the car for a few miles to heat up the fluid. Then fill to the mark.

Since you will be removing the pressure hose from the rack, you need an additional step at 4a. After starting the engine and running a minute or two, turn the steering to full lock (but don't force it - you don't need to make the belt slip) on each side several times. This is to purge any air from the rack.

Turning the steering lock-to-lock is probably not essential in your case, since the rack really shouldn't get that much air in it, if you let the pump circulate fluid for long enough to purge the control valve before turning the steering wheel. But just in case, I'd take the extra couple of minutes. It's clearly not helpful in my situation.