How to remove an address used for signing from the key pool? The message signing feature available in the Bitcoin-Qt client lets me prove that I own a Bitcoin address.  I don't wish for this address to ever be used for a future transaction however.  

Is there a way I can get the private key (and address) removed from the key pool so that it will not end up being assigned when I click "New Address" or used for the change address in some future transaction?

If so, what is the command and syntax?  (Presuming I do this from the debug window).
I am not a developer, but I believe that once you assign or create the address in a new account (you can name the account "Signing Key"), and then don't touch the account, this address will never be reused. Except only after there are some bitcoins sent to it.