Broken sudoers

Hey,

Got a bitter reminder not to edit sudoers without visudo. Don't have root password or it might not be set - no help there. As far as I know the remaining options are to either reinstall operating system or modify the file from external OS. Linux doesn't mount journaled hfs+ and apparently there's no way to disable journaling so it seems I'm screwed.

Is there any way to cleanly reset sudoers without root? If not, what would be the consequence of searching the string (2 lines) with disk hex editor, changing whitespace and running disk repail utility?