I used to use a combination of AuthentiKi and vJoy to control the trim wheel on my HC Bravo. It converted the trim to an axis, instead of button presses, allowing very smooth control of trim.
Here’s a link to a forum post that details it.
I’ve since abandoned that, and now use SPAD to control the trim wheel as button presses with a (configurable) resolution of .005 degrees per button press.
Using either method leaves my mouse wheel free to use as a zoom control.