My initial question was basically something along the lines of this: Clearing and setting the default home application
That question was answered to my satisfaction,
taking Pawan approach to more generic implementation:
public static void setComponentState(Context context, String packageName , String componentClassName, boolean enabled)
{
PackageManager pm = context.getApplicationContext().getPackageManager();
ComponentName componentName = new ComponentName(packageName, componentClassName);
int state = enabled ? PackageManager.COMPONENT_ENABLED_STATE_ENABLED : PackageManager.COMPONENT_ENABLED_STATE_DISABLED;
pm.setComponentEnabledSetting(componentName,
state,
PackageManager.DONT_KILL_APP);
}