I've been using EOS Utility to shoot tethered with the 5D Mark II. It's unstable and crappy, but it works to control the camera.
I searched hard to find out what the hotkeys are for camera control, but couldn't find anything (except for the space bar). So I experimented a bit and found the following hotkeys.
Change aperture: R and J keys. R to open up, J to close down.
Focus closer in Live View: C rough, T medium, W fine focus.
Focus further (towards infinity): R rough, N medium, V fine focus.
Hope this helps people. And if you find any more, please leave them in the comments!