Yes... This is possible. You would add this as a scanner "Study" and search for HTB. I know I have added it as a watchlist... I am working on some strategies tonight and will confirm this can be done. I imagine the condition is where the value = 'ETB' which is the only other option as far as I know.
Its really frustrating when you do all of your research on a stock and prepare to short it and then can't!