You should plan on saving your old water when you are making water change, and put them in a new garbage can. Place a heater, pump for circulation and a strip light on top (you can screw it up to the lid of trash can), voala, this is your curing station. I also drill a 3/4" hole about 10" down from the top of trash can act as an overflow. For the next 4-6 weeks after placing the new rock in, as you are making water change in the main tank, dump the water into the trash bin, excess water will flow out from the overflow hole you drilled. You shouldn't experience too much evaporation with the lid on.
After 4-6 weeks, the rock should be all cured and recovered from shipping damage. Unwanted critters (such as mantis) should've been dead by now as there has been no feeding at all. You can decide if you want to keep the trash can running or not. It can be served as prop tank or hospital tank as well.