If you have already extracted the Merge Modules from your installation CD (See building your "Rig") and you suspect Wise might have more up-to-date modules then this is the way to check and download in one shot.
-On the “Packaging server”, launch WPS
-Open Windows Installer Editor
-Open a blank WSI
-In Feature Details section select Merge Modules
-Click Add
-Click Ok
-Select any modules, click Download
-Download redistributables; click Next
-It retrieves the list from Wise and compares it to the Merge Modules already installed on the “packaging server”
-Check the required modules on the Available modules column
-Click Next
You can also get more of them at http://www.installsite.org/ under Merge Modules. Some of them are user-created.