Privent Auto mount a partition on 10.7.4
Add the following line to the /etc/fstab file:


  LABEL= none hfs ro,noauto


Being &lt;label&gt;the name of the encrypted volume.

If you are just wondering, ro means read only (you should use rwinstead, if you want to read and write after mount).

Note that the file could not exist, therefore you'll have create it. To do so just open /Applications/Utilities/Terminal and type:


sudo vi /etc/fstab
This will prompt the password. Type it. It won't be shown, don't worry.
Add the already mentioned line.
Hit Escape, type :wq, and hit Enter