Dave J, you should get it to raise a little slower by idling the engine. If your load is too great to lift at idle, increasing the RPMs bit-by-bit until it builds enough pressure should work for you.
When lowering, the valve is either open or closed; weight on the 3PH determines how fast it goes down. Inching the lever forward a bit then pulling it back to center is how I creep down -- but it's pretty herky-jerky, as Paul Simon describes in 'One-Trick Pony'.