Alternative to NSCollectionView in pre-OSX10.5, Cocotron?

NSCollectionView was introduced in OS X 10.5, and is not yet implemented in Cocotron.

I am trying to implement a small app that will allow creating properly packaged data files for an online service, which will then be uploaded by an administrator. More specifically, the user will create a collection of input and output data pairs, by dragging input and output files onto the window.

Currently the idea is that user drags a file, from the filename it's detected if it's the input or output filename (by default, input), and a view with icon and filename for input and output is added to collection view. Then, the second file is dropped on the "other" icon.

However, NSCollectionView does not appear in pre-10.5, and most of my users don't have Macs so I'll have to provide a Cocotron-built application. Not only that; I still don't fully understand KVC/KVO, and I really should understand everything that my code does. Hence, I need an alternative to NSCollectionView.

What alternative do I have to using NSCollectionView? (Any intuitive solution is appreciated, don't feel limited by the above description of my idea.)

To work with NSCollectionView, you need to not only understand KVC and KVO, but also Bindings.

There's code for an NSCollectionView clone that works on Tiger here.