Man, I learned a LOT today! I think I've managed to follow your ( in my eyes, cryptic ;-) steps and I think I actually made something which works. Unity really is a joy to work with :-)
Just in case someone is looking to do the same, I'm attaching the .cs
Instructions:
* DISCLAMER: USE AT YOUR OWN RISK. This is one of the first things I ever wrote in Unity, so it wouldn't hurt to have a look at the script and make sure for yourself it's safe to use.
* Add the .cs to a folder named Editor
* Create your .png and .bytes files in TexturePacker. They should both have the same name
* Select from within Unity the png atlas file(s)
* From the menu: 2D Toolkit/Make TexturePacker Sprite Collection
Now you'll find a new Material and the Sprite Collection in the same folder.
One question though, I did this:
tk2dRuntime.SpriteCollectionSize scs = tk2dRuntime.SpriteCollectionSize.Explicit( 1, 640 );
But I'm not sure those are the best values to use. Any suggestions?
edit: Updated version. Don't use the previous one!