How to Turn on IDENTITY_INSERT in SQL Server 2008?

Via SQL as per MSDN

SET IDENTITY_INSERT sometableWithIdentity ON
INSERT sometableWithIdentity (IdentityColumn, col2, col3, ...)
VALUES (AnIdentityValue, col2value, col3value, ...)
SET IDENTITY_INSERT sometableWithIdentity OFF

The complete error message tells you exactly what is wrong...

Cannot insert explicit value for identity column in table 'sometableWithIdentity' when IDENTITY_INSERT is set to OFF.

 http://stackoverflow.com/questions/7063501/how-to-turn-on-identity-insert-in-sql-server-2008