Do you know how to code in c or c++? Do you have a compiler? It shouldn't be that hard to send an occasional keystroke to the keyboard buffer. The hard part would be to send something that won't interfere with you typing.

While working at my last job, someone told me about one of my predecessors. He wrote a program that made a key click sound. So when his back was turned, it sounded like he was working to the casual observer. His plan fell apart when someone heard him snoring while his key click program was running. He was then able to work on a whole new program, unemployment.