I am sure you could find a way to do this, but frankly I don't believe doing something at the same time as riding the trainer (short of watching TV or listening to radio/music) to give a very good quality workout.

Workouts are much better when you are focusing on form, on how your body is moving, on engaging your core muscles, on pedalling in circles, etc. When we are reading at the same time, we get sloppy.

Sorry this doesn't answer your question. I would note however that the quantity of sweat (water + salt) that you loose when on the trainer is probably not a good thing to have around your computer.

p.s. If you could figure out a way to power up your computer with the energy you generate from cycling, that may be a motivation to work harder, though.