The developer of VUPlayer has been working on a new batch of filters for Adobe Audition. They were all just revised within the last week with new versions, but the latest is a new input filter for Adobe Audition that can read both Apple Lossless (ALAC) and M4A files. This new filter uses Quicktime 7 for the import. This ALAC filter, plus all his other wonderful Audition filters can be found at:
http://www.vuplayer.com/audition.php
FYI, the other filters can add support to Cool Edit and Adobe Audition to read/save FLAC, OGG, WMA. They can also read/import MOD and now M4A and ALAC. Many filters now have the feature to write tags as well.