disable and enable jobs

USE [msdb]
GO
EXEC msdb.dbo.sp_update_job @job_id=N'51228a93-6a7c-4086-8cc2-bd1dfa60677d',
@enabled=1
GO


USE [msdb]
GO
EXEC msdb.dbo.sp_update_job @job_id=N'51228a93-6a7c-4086-8cc2-bd1dfa60677d',
@enabled=0
GO

SSIS Package Configuration in SQL Server 2005

http://www.sql-server-performance.com/articles/dba/package_configuration_2005_p1.aspx