Funny you should ask. I just finished the steemconnect code that should bridge the gap between steem and non-steem users, and make it easy for steem users to have dual-citizen accounts. The final step will be adding a way to send the keys to the newly created steem users.

Given that I require them to put in a email address for account recovery might be the easiest way to send the keys, but that's a bridge to cross at another time.