Using Sophos CA to sign a CSR?

Hi,

Is there a way to use a Sophos CA (e.g., like the webmin CA) to sign a certificate signing request? I have a couple of network devices that are HTTPS only, and I would like to sign them with the Sophos CA, which I already have deployed to my admin hosts. I recognize this might have to be done via the CLI and openssl, but I can't quite figure out how to extract the relevant CA private keys.

Thanks.