I know I can use variable speed, but I am not too good at using the rocker switch to accelerate and decelerate smoothly. I wonder if there is a function that allows me to use constant zoom but it adds accelerate and decelerate automatically?

The only thing you can do is get an external zoom controller that doesn't have a rocker. I am using the ProZoom from Studio 1. It allows for a constant zoom speed for whatever you set the controller for.

Rob