Thermostat - permanently set heating or cooling mode

Is it possible to permanently set the thermostat in heating or cooling mode? I ask because the 5 degree minimum deadband is not going to work for me, and although someone has hinted at being adjustable, no one seems to be able to specify how to adjust this value. I am hoping permanently setting the heating and cooling modes for now will get me by until someone can prove that the 5 degree minimum deadband can be reduced.