Looking for a way to disable Press To Test is not a good idea.
Why do you think TI wants to block Ndless ? Because we could disable Press To Test and Nspires would no longer be allowed in tests so less people would buy Nspires.
And when less people have Nspires, less people code for Nspire.

This means that if your question already had an answer before, we wouldn't have gbc4nspire at the moment (this is only an example, I could have said NESpire or nDoom, etc)