That´s not possible at the moment to transfer an D3 char to another Battlenet account, but blizzard want to make it possible in the future.
When its possible you can do this:
You can create an battle net account with a 2nd name of the real owner.
The name of the D3 Accounts owner is: Hacker123.
Then you can open a battlenet Account with your name & the real owners name like: *yourname* - Hacker123.
Now you must transfer the Hacker123 char on your new account.
This works with WoW, but there is no transfer function for D3 atm.