One thing to consider Enola -- George has gamecocks as his avatar. Their behavior is quite different than most dual purpose breeds. Accomplishing this project on a gamecock type bird might be near impossible, whereas it is much easier on most of the dp breeds.
Decidedly incorrect Sydney Acres. Get some gamefowl and learn about them. Work with multiple generations of birds and invest time in learning how to handle them. Same techniques can be applied to any breed with similar results, You will find their behavior is exceptionally plastic and with proper handling skills you can have males with temperaments that are as docile with respect to humans as any breed you care to compare them with. This is before you engage in the selection process which can also result in behavioral even when holding husbandry techniques constant. Enola is correct about heritability of behavior and very limited number of generations can show results. Additionally, the approach / theory of keepers of gamefowl differs markedly just as is does with keepers of other forms of poultry.
George, I could take any pair of your birds and produce chicks, rear them to adulthood and have tame birds like I use for teaching. No genetic changes required. Those birds would be as sweet as anything anyone could compare to them.