'bffcreate' "unpacks" purely in the sense of doing a 'restore' from the 'backup' image on the original media, before creating a new 'backup' image on the disk of the selected component and running 'inutoc' - in effect a copy process, nothing particularly advanced. 

The purpose for that is to keep a copy on disk of some software that you might need with more ease than having to load installation media, in an environment where you may need to install from it repeatedly - otherwise you would use the original source media.  Such as on a NIM server, or one of those tricky little new partition suckers where you have one DVD drive and want the software around for  a partition with no access to the DVD drive say.

The Bull (or IBM) tools to create LPP packages out of your own files, in bff format, are intended for software developers to prepare their wares for an IBM style installation by the ultimate buyers of it. 

In the case of this question, correct me if I have misunderstood, we have a known list of files from a previously installed system (lslpp -f) but no access to the original source installation media, and no way to determine what was done in addition to restoring those files by way of set up by the installation process at the time. 

The question then was how to similarly install another system for testing purposes - and we'll leave aside any licensing issues there may be in this approach generally. 

An answer is for example:
lslpp -f what.ever | grep '^ */' | awk '{print $1}' | backup -iqvf /tmp/whatever

Then restore that on the other system - bearing in mind that you are restoring perhaps configuration files which are not then being merged in to your target system, are replacing and possibly messing up your target system if this LPP has anything to do with AIX per se.  Obviously this does not update the ODM to reflect that you have installed something, there would be no assistance therefore in de-installing it from AIX, beyond removing the individual files.

Which is where a change control tool is again a good idea, like that we use on these servers - see what changed, put it back, make the required changes in a more appropriate manner, log the new config for later.

The bffcreate command does nothing more than copy a chosen backup format file from installation media (i.e. original software CDs or DVDs) to disk and then run the inutoc to update/create the .toc for it.  So unless you have the original install image of your package (in which case you wouldn't need to be doing this) you can't use that.

From the lslpp -f list you have from the old installed system, you can create your own backup format file there, in the sense of using the backup command and making a backup of the chosen files:
cat list | backup -iqvf /tmp/mybff_file

That's not of course in the format for using installp, just a simple backup to be able to restore those files from on your chosen system.

Working with installp and the bff format to create your own installation images is a complete waste of time unless you are distributing software - which obviously you are not - and where you need to check on pre-requisites, update levels, etc.  That's what the Bull tools would do, but you don't need to. 

Now in addition to just restoring the files that make up the package on your target system, there may of course be other set up requirements, maybe scripts to run etc.  So that may not be the complete solution, and unless you have the original install image to check it, there's no realistic way you're going to work that out now.  So good luck with that one.

In the future, before installing something, it is helpful to have a change control tool on the target system.  A tool that monitors the configuration of the system and can report to you what has changed after you have installed something. 

In later versions of AIX there is a fileset for creating bff filesets, but you might find it simplier to use the tool that has been on the Bull Freeware site for years.

The name of your package may change with the BULL tool, but at least you will have a package.

Also, you could choose to not make a package at all, but just a bff and unpack it on the target system. The installp format is for verifying requisites (which the BULL tool will not help with if I remember correctly) and creating inventory entries to simplify removing a package (uninstall).

Many choices - all yours to make.

gl - keep us posted!

If you can find a system that has it installed, AND it is an installp installation (which are in bff file format) lslpp -f fileset.name will list the files (and links) in the installation.

This might be one way to reconstruct what you need.

Good luck!