I don't mean to sound like a naysayer - I am ALL FOR thinking outside of the box. But I would consider either figuring out a software method (change the program to not move if KEYDOWN is pressed - this may prove to be quite a larger programming challenge than it might appear at first glance) or consider another alternative. For example, buy 2 wireless keyboards. Set them to the same frequency. Broadcast on one and both get the data, no matter what your mouse is doing.

Would that work? You can get el cheapo keyboards for $10 - $20.

X-keys, however, are not wireless.