I think from what I've been reading today (I've actually been researching this topic most of the evening), the model itself needs to be within quads and no Tris, as in each face should have 4 vertices. After that, it can be converted to a .JSON file? I'm not entirely sure the programming aspect of it, But that is how it was explained in my reading.
Hope that helps! I'm sure someone with more knowledge on this topic will pop in and probably fill in the blanks. Just make sure the model is cleaned though. No triangles, no nGons either
Cheers! good luck.
EDIT: heyyoo! as SOON as I closed this thread, over on good ol page 8, I found a thread where anonym927 created a little program that does exactly what you are looking for! At least I Think he did? You can check it out for yourself. hope that helps!