Migrate admin permission from Exchange 2007 to Exchagne 2010

Hello, I'm looking for how to migrate the Exchange 2007 Admin Permission to Exchagne 2010.

For example, in Exchagne 2007, I can assigne a Admin user to full control for only 1 Exchagne 2007 in the Exchagne org. However, in the Exchagne 2010, I cannot find where can I set this option.  I can only grant full permission for all Exchagne 2010 server.

Anyone can teach me how to do this?

Thanks.