yes you can, I had one and my supplier gave me a fitting (like the one that goes on the pole hose), connected to pole tubing with a piece of 6mm push pipe on the end - it pushes into the top port of the merlin, you close the product and inlet of the merlin and turn your pump on to push pure water through the merlin allowing the flush to come out of the waste pipe.
works a treat and you can flush hundreds of litres through it if you wish!!
costs about £2 as well.