Hosed fstab, won't boot how to edit?

[Robert Moskowitz]

So I mistyped noatime in /etc/fstab; wished there was a way to test this 
first!

Anyway, since this is my ASUS Eee and my swap is on the SD card, by 
pulling the SD card the boot halts and puts me into Repair Filesystem mode.

Thing is /etx fstab is readonly.  vi fstab won't let me save the file.

I really don't want to do a complete reinstall yet.  I want to buy a 8Gb 
SD card first (and next time I am putting /usr on the SD card).  So how 
can I edit this?