The EOS tokens are ERC20 tokens for now, ERC20 tokens are on Ethereum protocol. So therefore, you would send the tokens to your ethereum address. The purpose of mapping is so that the snapshot can map your erc20 tokens to your EOS keypair after the erc20 tokens have been frozen and after the Genesis block on the EOS blockchain sometime around June 2nd-3rd 2018 2018
RE: How to update the EOS public key mapped/registered to your ETH Address with MyEtherWallet (MEW)