Might be quite doable but if you really want to power the microwave from the cycle trainer you have to rig up an buffer battery. I rather doubt that even an very well worked out person can do >400 Watts for any length of time.
But living of "self cycled" microwave dinners doesn't sound like an healthy livestyle to me.
Btw: A 'Cycle to play WoW' device seems more promising to me. Make a deal with Blizzard that they will up drop rates depending on the rpms.
