You have to work with public and private keys to do that but I think it's possible.  I've never done it myself though.
The second half of this WIKI explains it:

http://wiki.bitshares.org/index.php/Best_Practices/Cold_Storage

Look up the help entry in the console for wallet_import_private_key and you will see how to deal with the account names.

Does anyone know if you can import a registered account from one wallet to another? If so, how.
Thx