I just needed a quick way to adjust parameters in an actor

Another quick way is to use the 'modifiers' input on the normal Mouse Watcher actor. If you set it to 'shf' (shift) for example, the numbers in the outputs will only change while you're holding down the Shift key.

Good question.... in the stage mouse watcher actor you can monitor some aspects of the mouse scroll wheel, but because it's an endless scroll - unlike the x and y position of the mouse itself - I don't think there can be a definitive "you've scrolled up 10 lines" kind of value. Is that what you were looking for?