Switching window managers from command line

[GammaPoint]

Hi, I want to swtich my window manager from the command line. I usually run compiz fusion (leigh's version) and I can switch to metacity by typing " metacity --replace &"

However, typing "compiz --replace &" or "compiz-fusion --replace &" does not take me back to the working version of compiz that I can get back to if I simply use my mouse and select the window manager from the compiz icon (it instead loads something that looks like a buggy compiz) Does anyone know how I could find out what the correct word to use is here, or is this for some reason not possible?

Thanks.