New: The previous version is rubbish! Just add your MP3 encoded files to iTunes library, select the entire album, choose get info from right-clicking it, go to the last tab (options) and select: Part of a compilation, remember position, skip when shuffling and in media type, Audibook. And you are done in a moment.
Time-wasting version by Google: This is just to remind myself how to do this simple thing. I got the information from here (via Google).
- Add your MP3 to your iTunes library
- Select that file in iTunes
- Right-click, convert to AAC (or create AAC copy)
- Remove both instances in your iTunes library (without deleting files!)
- Go to the folder where the file is
- Remove the MP3 version (if you want)
- Go to your iTunes Library folder (Documents-Music-iTunes-iTunes Library-path to your file)
- Move it to where you like it to be
- Change the extension of the file from M3A to M3B
- Add this file to iTunes
- You are done!
- Now you can edit file info and properties as usual.