Years ago InstallShield released a product called the IAR ( InstallShield Application Repackager ) that snapshotted application setups and created InstallShield 5.x projects.
I can't recall if that ever left beta or not. Is it still around?
Otherwise you can still generate a report in Admin Studio Repackager, filter out all the COM stuff since you'll be using SelfRegistration and just piece together your project in ISPro by hand.