I built a script for ReaJS to create smooth “controller ramps”, which could help you do that:
Insert ReaJS in your project and load the script “midi_CC_smoother” (you’ll need to put the script linked above into your ReaJS MIDI effects folder first…
create a MIDI route from ReaJS to your plugin
Set the parameters of the script to your liking. In your case, you’ll want to set the “Controller” to 1 (Mod Wheel) and keep the step increment at 1; play with the “ms per step” parameter for ramp speed
Use bindings to send the target value to the script - it will ramp from its current state to the target value
the script will use controllers sent on MIDI channel 1 as “ramp targets” and move smoothly towards them; when you send controllers on MIDI channel 2, it will immediately jump to them without smoothing. The output will always be on channel 1
if you control modwheel both from your keyboard AND via bindings, you’ll want to send your keyboard modwheel commands through ReaJS on channel 2 to make sure they get interpreted directly, and send your automation bindings via channel 1, so they get smoothed. This way, the script always “knows” the current state of the modwheel and where to smooth from.
Give it a try - it can be pretty useful! I use this script for smooth volume changes between song states, e.g. to smoothly fade in a string layer.
An alternative approach is to have MIDI files with fixed controller ramps in them, load them into a media player and start them via bindings. If you don’t need a variable start or target, that can work nicely for volume or controller ramps.