In the script driver add a handler to the event IR.EVENT_CHANNEL_SET, add case on the indicated channel - setDimmer. If the incoming value is empty, show a popup with a level where a user can set values. When the popup is shown the handler's work is finished. The popup must have a button to save the set value. The button must have a handler, that gets values from the level and sets the value in the Advanced Macroses MDX register, for example: