You are still going to need some sort of zone board to turn the unit on and off unless it is just going to run all the time and dump the air outside when no zones are calling. Which defeats the entire purpose of what you are doing. Not only does the zone control have safeties built in, it enables multiple zones to turn the equipment on and off as needed. By the time you purchase this zone board and these motorized registers, which I'm sure aren't cheap. You have just purchased a standard zoning system.
I like DIY'ers. They pay better to fix.