Yup, i installed one. I put it inside the aft compartment where the shore power cords go in. 1 10' piece of 1/2" pex tubing and a 1/2" sharkbite T fitting. I Teed in to the water system on the inlet side of the water heater.
It doesn't matter where in the system you t in as long as it is after the water pump. The freshwater pump has a check valve to keep the pressure in the system.
I used this water inlet http://www.starmarinedepot.com/jabsc...TgsBoCF4vw_wcB
The hose goes in along with my power cords through the slot in the aft compartment door.
I hooked the section of pex to the inlet, cut the hole in the floor of the compartment, then fed the tubing in through the hole. Went down in the engine room, and pulled it up over the water heater, then screwed down the inlet, so that i didnt have to make a connection back there behind the starboard engine.
In the top of this picture you can see the t where the inlet line joins the system.