
I tried to find the UI control in the Object Model browser via the name(s) (and others that might be similar) that InDesign C++ SDK has for this sort of control but ScriptUI does not have that.
IMO, you will have to go with an alternate approach i.e. create buttons with similar appearance, place them close to the edit-box and react on the notifications that these buttons will send on change.
Other than that, May I request that you post this to Adobe InDesign Developer forum as well. Please log a bug on Adobe InDesign as well for details as well. That should get you the right approach if there is any as they also might be using internally.