I'm unsure the leg motions would work properly, but the basic Poser solution is to turn on Inverse Kinematics for the legs, and then parent the feet to the pedals. Most of the work is in the last little bit of getting things right, but I think theis would reach the level of a good toon, especially for a medium-close shot. Think rollers and green-screen, or an earlier generation's use of back projection: do you need to show the whole thing?