Found old reply...

Have to change media type to 'Audiobook' instead of leaving it as 'Music'.

The 'Audiobook' option will 'change' the file so it's read in 'Books' while leaving it the 'Music' option to read in 'Music'.

If iTunes have that 'REMEMBER PLAYBACK OPTION' for mp3 (labeled OTHER THAN audiobook), then you should Implement that Feature as well!