Apparently, you can do it through the DiskUtility (Applicatons:untilites) but on my powerbook it is greyed out...
You could try this though, in terminal... (
entirely at your own risk, back up your important stuff first)
Code:
sudo diskutil disableJournal /
From here
I did a "man diskutil" and there is an disableJournal option. Its nothing new thought, its been there since 10.2.2?