Yep exactly, use the low pressure (screwclamp) side.
What I do is plug that end of the pump, and point the hose into a bucket. Empty most of the reservoir, the stuff that just spilled all over the floor....
Then without starting, crank the motor, and add new fluid into reservoir. This pumps (one-way) fluid thru the system, and flushes it.
Put the hose back on, and top off reservoir. CRANK steering lock to lock to remove air bubbles, and top off reservoir.