I work with InstallShield a lot, as my employer has dozens of installers that need to be maintained. I also often need to base a new installer on an existing one. The simplest way to do this is to simply copy the old InstallShield project and change project-specific settings. Unfortunately, this necessitates changing a bunch of GUIDs in the project file so that they don’t clash with the old installation. Doing so from the InstallShield UI is a pain, so I wrote a quick script to take care of it. If using this with InstallShield projects, make sure they’re saved in XML format (rather than binary; but if you’re using binary format with a source control system you have my sympathy anyway).
The script just scans through the input file looking for UUIDs and maintains a map from the UUIDs it’s found to the ones it’s generated. Simple enough, but it should come in handy — I’m only embarrassed that it took me over a year to write this!