So how do you get the work hours to qualify for the test?
The word "apprenticeship" comes to mind. Also, until a venue requires only certified riggers one can work and/or receive OJT that will count. Also remember that both "up" and "down" rigging apply.
I am not yet qualified to sit for the test, but our Local has 3 venues that do not require 100% certified rigging crew, so I am able to rig in those facilities and my work hours count. Our local has begun in-house training again, so we also have an experienced/certified head rigger dealing with trainees. We've found it harder to train good ground riggers than to train good up-riggers. YMMV.