I use a small fountain pump and a backflush
adapter. Fill a bucket with water and BLC, throw the faucet in and attach the backflush adapter to the pump. Then take apart the ball lock fitting on and put it in the bucket. Turn on the pump and let it circulate for a couple of minutes. Then I'll put the pump in a bucket of plain warm water to rinse the cleaner.
Very simple and much easier than the old spray bottle I used before. Total cost is around $35.