Changing default Audio track in a DVD?

How do I change a DVD so it plays a different Audio track as default?

The DVD I have has DD2.0 and DD5.1 audio and uses the DD2.0 as default, how do I change it so it defaults to DD5.1 when played?

Can It be done in ifoedit, if so how?

Sorted!

Found a nice guide on how to change default audio using Ifoedit, if anyones interested:

http://forum.doom9.org/showthread.php?s=&threadid=60444