Would also be interested in replies to this.
Things that I could think of:
*Listening to a wide variety of music as often as possible
*Downloading free aural programs like Good Ear and Aurelia (demo version)
*If you can play the piano play cadences and things like that to yourself until you know them
*Hofnote is a good aural site which needs paying but it helps
It won't happen overnight, so be prepared for it to take time