Now your talking!! or rather, now I get the picture..

I think a high speed glider would be the go- shot from the co2launcher at a constant angle with two channels to allow you to steer it onto target. It would take some serious skill to actually HIT the target, but I think you could do it.
Have you seen those micro R/C cars(1 1/2 inches long)- they run of a single 50mah nicad and are dirt cheap- about U.S$15... [8D]
It will take you a bit of experimentation to get one flying, but I am pretty confident a fast, r/c glider is do able... who knows you may find enough power to maintain altitude- but I would think a glided missile would be the way to go.
J.M