while i agree that engine braking with a gasoline engine is more of a suggestion to slow down, it does work if the operator knows how to do it properly.
ideally, you keep the vehicle speed in a range where the decent can be almost entirely controlled with engine braking. plan ahead to avoid needing to slow down suddenly. RPMs need to be above 1500 on EEC-IV vehicles in order for the PCM to kill the injectors (you dont draw much of a vacuum at those speeds anyway), and braking in direct and overdrive gives the tires too much mechanical advantage on the engine to do much. i slow the vehicle to 65MPH or so (you dont want all that extra inertia moving any faster than that on a hill anyway), downshift into 3rd (thats about 4,000RPM with my gearing), and only use the service brakes to maintain engine speed if necissary.
i drove like this without trailer brakes through the canadian rockies with about 3,000lbs behind the ranger and i was rarely on the brakes. when towing my little 1,200lb boat, i almost never use the brakes.