Assigning HotkeysΒΆ
To assign a hotkey you can use Assign Hotkeys...
option in flyout menu. Simply select the Toggle Modificator hotkey button and assign a hotkey. Using this window you can assing any keys that Photoshop allows;
In conjuction with a Close on Click
option enabled, the panel can be hidden most of the times, called when needed and then automatically closed after an adjustment has been made.