‘Live’ slider in addon settings

Is it possible to have a slider in your addon’s settings that behaves in a ‘live’ manner – e.g. to control the brightness of an external screen? So as the slider changes from 0 to 100, an action e.g.

Code:
action="RunScript($ID,changeBrightness,currentSliderValue)"

…is called?

At the moment I have it all working but they have to set the slider value, save the setting, then come back in to setting and hit a button that calls the action…which is… naff.