What other OS? Windows? I don't think Windows will know what to do with a YUM cache, and Linux programs generally don't run on Windows anyhow, so I'm not sure what the point would be. If you're dual booting your Cent 6.2 with another Linux distro that uses yum, in principle it is possible, but I think it's a very bad idea since each distro maintains its own repositories and packages. You could share the same cache among multiple CentOS 6.2 installs, but if you want to do that why not just set up your own local mirror instead?
You need to give more details about your setup and what you're trying to accomplish here, but offhand it doesn't sound like a good idea at all.