How would you install any other OS within VMWare? Could you install them from their respective CDs or do you have to buy special 'addons' from VMWare themselves in order to get another OS to work? If it's the former, then could you not simply download a distro, burn it to CD and install from their?
I've never used VMWare (as you may have guessed), but I have used bochs and tried to get plex86 (the latter being a free VMWare type thing, also called freeMWare), and to install another OS, you have to make an image of the installation media (CD), and set it to 'boot' from the image file.
Sorry for the vaguity of my answer, but I've never used it as it's a bit too pricey for my wallet.