That's a really good question, and the answer might be a bit hard to understand. Probably the reason that it seems like it would be possible is because the movements of the human body (and animals, too) are controled by teeny tiny cells called nerves. Although they're very thin, they can be really long, and they connect the brain to every other part of the body. When the brain wants to tell a part of the body to do something, it sends a really small electrical signal through the nerves to the muscles it's trying to move. These electrical signals work because between the inside and the outside of the cell, it's polar. This means that on one side of the cell's membrane (it's wall), there's lots of atoms with extra electrons, and on the other side, there's lots of atoms that are missing electrons.
When a signal is sent through the nerve, it opens up little things called ion channels in the cell membrane. These let the charges get from one side of the membrane to the other so they can even out to the same total amount of electrons on each side. When this happens, it actually creates a bit of a chain reaction that travels all the way from one end of the cell to the other. (Little pumps in the cell come along after it and pump the charges back where they came from so it can happen again.) This means that the signal can get from the brain at one end of these very long cells all the way to the muscles at the other end.
So electrons /are/ very important in how we tell our muscles to move. But let's say we did put a high intensity stream of electrons into a person. It would be /really/ hard (probably impossible) to tell those electrons exactly where to go, since there's so many nerve cells, and they're all so small. And how would you be able to get just the right amount of charge to hit each nerve? Even if you could, you'd probably succeed in electrocuting the person before the charges were able to do what you wanted them to do.
Basically, the human (and animal) body is so incredibly complicated that we can't even begin to figure out all the ways it works. It's /much/ more complicated than even the smartest computers in the world, and no one understands it well enough to even come close to being able to control it (with electron streams or anything else). So I believe that I can safely say that the answer to your question is most definitely 'no.'
(published on 10/22/2007)