This is where I plug my plugin, which does light up the keys, but which is triggered by a press of Key_CapsLock instead of a double tap of a shift key. It may or may not be close enough to the functionality you want. I’m not sure how it would behave if you used TapDance to send the Key_CapsLock event instead of binding it somewhere in your keymap, but if you try it and it works in combination with TapDance report back!