Hey Claudio,
Just saw your question.
I'm using Cakewalk in the rare cases when I need any DAW interventions in my life, but in this case that's irrelevant, it works the same way with any DAW.
Once you have your keyboard connected to the PC, just arm a track and start recording, press any of the Art buttons and stop the recording. Than go to the track and look for recorded controller/s in the track, it's that easy. That's the quick and dirty way to get around similar cases, at leas that's how I do it instead of digging deep in the reference manuals.
Just tried that myself for the experiment, and it comes out that Art1 is CC#80, Art2 is CC#81, or it was the other way round, didn't noticed which one I pressed first, you try it for yourself and see. Subsequently value 127 is ON, 0 is OFF. Enjoy!
Hope that was helpful.
Cheers!
Valentin