Question logging in locally when on a domain on windows 7

I know that to log onto a local account when on the domain in windows 7 you would use .\ before the username. ex ( .\larry ). I also understand that typing the user name "administrator" automatically sets it from domain to local. My question is, is there something I can change, such as the registry or user profile so that a different account ( such as larry) does the same as administrator,...