I've used the raw water pump coiled hose, which has a soft rubber tip on the handheld sprayer. I force it against the hole inside the strainer going TO the water pump (it's not a good fit). Let it run for awhile (seconds, not a minute), or until water starts to exit the through-hull (it may or may not). Then start up the A/C and continue to spray into the strainer 'cup' towards the hole, while immediately replacing the basket and clear strainer cap. I sometimes first shut off the through-hull valve to help initially fill the strainer cup, force the water to the pump as described before, and then quickly open it up (after it overflows), start the engine, and then immediately put the cap back on. It takes two people, it's messy, it's not foolproof, but it works for me more times than not. What pisses me off, is when it losses prime again 10 minutes later, and I have to do it all again.
Todd
Todd