MODIFYSCRIPT Package Variable Task Usage 
MODIFYSCRIPT Package Variable is a custom task that can be inserted into any package in the Data Manager to modify the package itself, when executed. When this task runs, it modifies the properties of objects contained in the package (such as tasks and connections), according to some user-defined instructions specified in the task itself. MODIFYSCRIPT provides you with a single interface from which you can specify a modification for any property within the package. You can use this task to automate processes by replacing user-provided information with script-provided information.
Note
This section explains how to use MODIFYSCRIPT Package Variables to modify the behavior of packages at runtime. For help on building packages, see Microsoft SQL Server documentation. In the sample packages included with Planning and Consolidation, the MODIFYSCRIPT variable must be defined as Package Variable (and MODIFYSCRIPT must be capitalized in SSIS Variables.) Some knowledge of Microsoft SSIS packages is recommended for working with the MODIFYSCRIPT variable.