I use scp to copy my public keys. Since ssh has to be set up anyway, it seems the easiest way. try:
scp publickeyfile firstname.lastname@example.org
add it to your authorized_keys file by logging into the remote as you and running $ cat publickey >>.ssh/authorized_keys
If you have only one authorized_key, I would guess you could just $ mv publickey .ssh/authorized_keys, but I have several different systems.
Doing the same thing in reverse from the remote to the local allows ssh host either way without passwords.