Is it Possible to Manually Organise Imported Movie Extras in iTunes I'm trying to organise a bunch of movie files that I've acquired from various sources, including my own DVDs, into iTunes.

However, one thing I'm uncertain of are the extras, things like deleted scenes, making of documentaries etc. Unfortunately none of the files I'm importing are available on the iTunes Store (as otherwise that's where I would have got them).

So what I'm wondering is, how is content from the iTunes store organised in relation to extras, and how can I do it myself for imported content?
When sold from iTunes, extras come in a package called (appropriately enough) iTunes Extras. An XML document describes the layout of the extras and where they are located. Apple provides a specification document that you could use if you wanted to build your own package.