I don't know if you can do what your thinking but it might be in here if it exists. From what I know you can only change it for like one operation in fact being able to see what shape it's in is important to being able to tell what it's doing.
I did see something while searching for that site that suggests you can upload different operating systems onto these types calculators however I know nothing about that.
I think it would be possible. Hard, but possible. You would have to interfere with the graphics card, to counteract what the calculator's OS does with the blinking. Messy stuff. I just have to ask, WHY?!?!?