Secure Login in Drupal
If you're already using OpenID, then that should work, but if you dont want to add yet another module and you have access to a server over ssh, you can temporarily route all traffic in a tunnel through the server, which will effectively secure all internet traffic, and allow you to connect to the site and send the password "in the clear" as it were over HTTP, but the SSH tunnel would encrypt it before it left your machine.

If you happen to be on a mac, i highly recommend using Sidestep.app to facilitate quickly connecting/disconnecting from the tunnel.

http://chetansurpur.com/projects/sidestep/

For this to really work for you and not be a complete annoyance, I repeat, you need to have SSH access to a server already set up, ideally, with public key access configured.