Thanks for all the tips. I had been going right up against DK, just one pixel away. Doing that, you don't have to push the joystick in order to get the bonus. But, as noted, you will sometimes bump the joystick too far and die from "touching" him. I suppose that pushing the joystick either left or right mid-jump is a habit that you have to learn so that it becomes "automatic".
Also, thanks a BUNCH for the tip regarding pushing the jump button to trick the fireballs. I had noticed that Chien was doing this on the barrel boards, but couldn't figure out why. He would push the button repeatedly as the hammer was striking a barrel. When i tried this, the point value for ALL of the busted barrels never went over 300. I suppose he was doing this out of habit from the rivets boards?