this should be possible. I would create a rule set which matches the URLs of Scripd. I think a list like this should be suitable:
URL.Host matches in list <Scripd Hosts>
and the list "Scripd Hosts" should contain:
So you have a rule set that matches for Scripd only. Now you could place a rule like:
Command.Name equals "POST
MediaType.EnsuredTypes at least one in list Documents
By doing so you will have Scripd usable, but uploading Documents should be blocked. You can add additions MediaTypes as you like.
This is only a basic idea - I did not try it, so no warranties if it works :-)
I'd say overall this works pretty good and I have tested and fully implemented it. The one caveat is that it doesn't allow you to log in, but in the overall scheme of things were fine with that at the moment. I tested this against the various methods of upload. The standard upload file button, the text box paste upload, as well as the desktop installer msi that you can install. With the msi, because you can't log in ultimately that tool fails.
Good stuff, thanks again!