Yes, this is very easily done. It is very simple and works so well. First measure the dimensions of the rear of the unit. Call a heating and ducting company and have then fabricate you a box. Most ducting companies will do custom fabrication for very reasonable prices. Have them construct you a box 2 feet deep with a 4 inch round duct at the end. Have the box built so it fits perfectly over the rear of your window AC unit. The idea of the box is trap the heat produced from the rear of the unit. Once you have a fabricated steel box fasten it with self tapping screws to the AC unit. Attach a 4″ inline fan to the 4″ duct on your box to suck the heat from the AC unit. Vent the 4″ duct out a dryer duct or through the furnace to remove the heat the AC unit produces. It may seem like a lot but it is a simple procedure and it will really reduce the heat in your grow room.