Can iTunes convert a file and replace the old file with the new one?

Question

I am trying to convert my wav files to Apple Lossless to save some space. How can I convert the files and make them replace the old files? Right now it just converts new files so that I end up with two files. I have thousands I want to convert and just replace the old ones.
I have an external program that will do it for me, however if I go that route then when my ITunes files are converted to lossless files I need to re-link the files as they show up with the ! showing they are missing. That would mean manually re-linking every song, which would take forever unless there is a way to mass re-link all the files.

Answer 1

iTunes does not see the newly created files as the same file because they are not the same file.  They are new, different files.  If you have a track that is 1234.wav and you create 1234.mp3 it simply isn't the same file and you can't trick iTunes into thinking it is.  iTunes will handle it as a brand new file.
Check Dougscripts web site for scripts which help modifying tag data.  However, I suspect you won't find any doing exactly what you want doing.  Some tag data are only accessible by iTunes itself.
As for playlists, there's things you can try though they may be more effort than they are worth.  For example, you could add a special code for each playlist to some element of a tag (e.g., grouping).  Convert the file, then make a smart playlist selecting for the code you added to the group of tracks in the old playlist.  If you have hundreds of playlists with a dozen tracks each this will be a grand nuisance.  If it is a handful of playlists with hundreds of tracks each this might be worth it.
Another way to preserve playlists would be to edit the .xml copy of the iTunes library file, replacing ".wav" with ".mp3" or whatever format you are using.  However, this won't help with play counts because that is only stored in the .itl copy of the file which you cannot edit.