Snapshot persistence with live build 3.0

[Santiago <santiago-x@freenet.de>]

Hello,

I actual use a squeeze live image which is build with live build 2.x and 
I want to migrate it to wheezy with live build 3.0.

The home folder should be persistent. Therefore I have a partition 
labeled "home-rw". I already adjusted it to the label "persistence" and 
created a configuration file persistence.conf. This is working fine.

Additionally I have a read-only partition labeled "live-sn".
How can I realize this with live build 3.0?

I already tried the following:
- new label "persistence"
- create a persistence.conf with the following entry "/ union"
- add the the parameter read-only=/dev/sdx2

Any suggestions?

Many thanks in advance.