Yeah, to wash the keg without removing the stem you need a pump, a D sanke tap with your valves on it like the picture above, and a CO2 system. Turn your keg upside down and set it on something, I used to use two other kegs to prop it up. Drain and depressurize the keg vial the gas side. rinse a cold rinse up through the liquid side, and then pump your pbw solution through the same side. rinse well, two 30 second rinses works well, fully draining between each rinse. purge with co2. thats your basic keg washing procedure.