There's a great JS plugin from Talagan called MIDI CC Mapper X - see, e.g.:
https://forum.cockos.com/showthread.php?t=172630
I use it all the time with my Novation Launchkey - it can map a bunch of sliders, knobs, and buttons at once. You can move "slider 1" on the plugin, get it to learn the Novation Slider 1 CC, and then have it output a different CC to your VST (or hardware synth for that matter). Then set up Slider 2, each of the faders, etc. etc. My Launchkey can control all the drawbars on a VST Hammond organ now, with the buttons turning Leslie on and off, the knobs controlling the overdrive amount, etc.
Also, a little while ago Talagan came to the rescue and wrote a script that takes a momentary switch and turns it into an on/off toggle switch - I use that with MIDI Mapper X also - that way the buttons on my Launchkey can turn an effect on a synth on with one press, off with the next, e.g.:
https://forum.cockos.com/showthread.php?t=238532
$0.02