A supplement to Matt's answer: One of the cool things about Studio One is the Control Link system which you can use as a bridge between your External Device's MIDI data (like a foot controller) and the automation system. If the foot controller sends out MIDI you can basically control any VST automation parameter and a whole lot more with it in Studio One by mapping the MIDI CC's to the Control Link system to control automation. You might to have to set it up yourself though, it isn't linked out of the box (not that hard, there are some resources on the net on how to create your own device maps).