Session guitar

The question is not about Scaler, but about that program, which is sure to be used by many in this forum as well. I would like to ask, is this possible to call myself? I mean, it wouldn’t use those ready-made stuff. If I press a contact then it takes them into account. How do I get it off and play the midi keyboards what I personally want? Is this possible? I haven’t found a place to get that.