Inno Setup looks like a great tool! I don't know Pascal or Delphi, but I work in software so I thought I'd hit the forums see what I could find...
First, I'm wondering if there is any way when you are creating the installer to customize/add your own functions in Pascal? In other words does inno setup/delphi give you a finite number of options, or can you get into the weeds a little and add your own code? If so (and if you're interested of course :) ) here are some links I found that could have some good ideas / examples / useful functions:
Pascal Scripting: CreateInputFilePage:
http://www.jrsoftware.org/ishelp/index.php?topic=isxfunc_createinputfilepage
example? http://www.jrsoftware.org/ishelp/index.php?topic=scriptclasses&anchor=TInputFileWizardPage
Pascal Scripting: FileSearch http://www.jrsoftware.org/ishelp/index.php?topic=scriptfunctions
Pascal Scripting: GetOpenFileName
http://www.jrsoftware.org/ishelp/index.php?topic=isxfunc_getopenfilename
Here's another one that I only had time to look at briefly, but looked pretty interesting and mentioned searching/filtering:
http://torry.net/pages.php?id=55&sort=ID
these bullets caught my eye...
Sections are now searchable groups and show the files that contain them.
Structures are now searchable groups and show the files that contain them.
toolbars and db dialogs to Find, Filter, Sort, Export, Print. I don't know if any of that is useful - if so, great! If not, no problem. Thanks for the work you've done already!