By stake an address, I presume you mean save an email address?
Unfortunately can't do this as it requires the password to save.
He means you should post your Bitcoin address on this topic :
https://bitcointalk.org/index.php?topic=996318.2800once you do that , people will quote your post and you will be able to sign message on the future to proove ownership of the account later . In case anything happens (hacked , stolen , lost password) , theymos will recover the account .
Make sure to use an address from where you can sign (Electrum , Multibit HD , Bitcoin Core etc ..) and not exchanges because you don't own the private keys needed to sign a messagee there .