I really don't know anything about spinnakers, but I think you first have to figure out where to put the turning blocks or track and maybe even another set of winches.
Those cleats on the deck don't seem too good to me. The line would have to be flat to the deck before they would even work. How could that work with the line coming off the winch?
With a spinnaker, you might even want cam cleats to blow the chute quickly.
There's a little something on the Harken website
http://www.harken.com/rigtips/spinnaker.php