Using GPScript you can catch keystrokes and do something. But unlike buttons of your MIDI controller, which usually send a MIDI value 127 when pushed and a value 0 when released, keystrokes don’t have a release value. We could imagine a GPScript sending a CC# message with value 127 each time a keystroke is detected. But this would mean that the only option to control a widget with this is to have the momentary to latching option enable. We could also imagine a GPScript sending a CC# message with value 127 and a 0 after a short period of time to simulate the detection of a released key. Well, this is not something natural. So, I am wondering if, as a new user, you wouldn’t rather start with the regular GP functions ?
There is also another option using a Scriptlet, if you need a few more buttons you don’t have on your MIDI controller: