Check http://www.linuxquestions.org/linux/answers/Networking/Public_key_authentication_with_ssh
The public key is what needs to be pasted on the router. It will look somewhat like this:
The private key will be what you use to authenticate yourself (check your client's instructions if not using a Linux command prompt to connect to the router).
If you already have a private/public keypair, then yes you can reuse it.
thank you. this worked like a charm. Its funny how rusty the brain gets for some things. appreciate it.