Trying to Replicate Bali/Somfy Stock Remote Behavior (holding button lowers until released)

I have some Bali/Somfy shades with many rules set up via SharpTools and WebCore. All works well.
The one thing I’ve not figured out is how to replicate the behavior of the stock remotes. On the stock remotes, when you press and release the down button, the shades close - easy enough. When you hold that same button however the shades will lower as long as you’re holding them. Release the button and they stop moving. The inverse is of course true for the up button.

As I write this, it’s really a broader question of “hold to dim” logic. I’ve not seen any way to do this, but clearly the z-wave remote that comes with it does it somehow, as the remote itself shows up in ST (so it’s not as if the remote using a proprietary protocol).