How to mount /dev/disk1 with write permissions from Recovery Mode?
When started in the Recovery Partition, choose Disk Utility from the list and click Continue. I'm assuming you are using 10.8.5 Mountain Lion.



Select Macintosh HD in the list of volumes on the left side and click Mount button on the toolbar. The volume will be mounted read-write and you can close Disk Utility, open Terminal and type:

cd /Volumes/Macintosh\ HD/etc


and work on files in that folder as you please.

Note that /private/etc and /etc are the same folders.