Copy/paste of this discussion from the grasshopper forum:
Reply by Mathieu Huard yesterday
Thanks for the kind words!
We have been considering a lot of features for the online viewer, but so far we have decided to keep it simple and open. We will slowly add to it but for now the focus is on improving the rendering.
Once the code is clean enough, we will make it open source so that anyone can add specific features to it. Your case fits well in this category. You can already communicate any data between the viewer and Grasshopper, the only missing part is the UI you describe.
In the meantime, since ShapeDiver supports text outputs, some users have been simply displaying values directly in the model:
Another newly added option is to use parametric textures for displaying text not as 3D elements but as images on the geometry:
This is nowhere near the nice interface you describe, but a good place to start.
Reply by owe yesterday
Aha, very interesting Mathieu, that might do it until you develop Shapedriver further.
Thanks a lot!!