Sure! - you could set up a mod wheel, fader, knob, key, button....any kind of physical controller to send a CC2 message. Most midi keyboards will let you change the CC number which is attached to a particular knob, button, slider...ect
Sorry, I'm not au fait with Ableton (Cubase user here) but its pretty similar on all DAWs.
You would need to create a midi track and instead of inserting note data you send CC data -just make sure your sending on the right channel too. In Cubase there is another lane underneath the note lane where you can draw the CC data into. Probably should have a quick look in the Ableton manual or maybe another user can help you with the specifics here?
You seem to be thinking about it right. Its just a system that lets you have more control over parameters.
CC"x" lets me change the "y" parameter of an instrument. Lets you automate or have realtime control over things. Or a bit like a universal remote control for your TV and Video but for your synths and midi speaking devices.
